Maybe (RxJava Javadoc 3.0.0-RC7)

java.lang.Object
- io.reactivex.rxjava3.core.Maybe<T>

Type Parameters:

T - the value type

All Implemented Interfaces:

MaybeSource<T>

Direct Known Subclasses:

MaybeSubject
```
public abstract class Maybe<T>
extends Object
implements MaybeSource<T>
```
The Maybe class represents a deferred computation and emission of a single value, no value at all or an exception.
The Maybe class implements the MaybeSource base interface and the default consumer type it interacts with is the MaybeObserver via the subscribe(MaybeObserver) method.
The Maybe operates with the following sequential protocol:
```
 onSubscribe (onSuccess | onError | onComplete)?
 
```
Note that onSuccess, onError and onComplete are mutually exclusive events; unlike Observable, onSuccess is never followed by onError or onComplete.
Like Observable, a running Maybe can be stopped through the Disposable instance provided to consumers through MaybeObserver.onSubscribe(io.reactivex.rxjava3.disposables.Disposable).
Like an Observable, a Maybe is lazy, can be either "hot" or "cold", synchronous or asynchronous. Maybe instances returned by the methods of this class are cold and there is a standard hot implementation in the form of a subject: MaybeSubject.
The documentation for this class makes use of marble diagrams. The following legend explains these diagrams:

See Flowable or Observable for the implementation of the Reactive Pattern for a stream or vector of values.
Example:
```
 Disposable d = Maybe.just("Hello World")
 .delay(10, TimeUnit.SECONDS, Schedulers.io())
 .subscribeWith(new DisposableMaybeObserver<String>() {
 @Override
 public void onStart() {
 System.out.println("Started");
 }

 @Override
 public void onSuccess(String value) {
 System.out.println("Success: " + value);
 }

 @Override
 public void onError(Throwable error) {
 error.printStackTrace();
 }

 @Override
 public void onComplete() {
 System.out.println("Done!");
 }
 });
 
 Thread.sleep(5000);
 
 d.dispose();
 
```
Note that by design, subscriptions via subscribe(MaybeObserver) can't be disposed from the outside (hence the void return of the subscribe(MaybeObserver) method) and it is the responsibility of the implementor of the MaybeObserver to allow this to happen. RxJava supports such usage with the standard DisposableMaybeObserver instance. For convenience, the subscribeWith(MaybeObserver) method is provided as well to allow working with a MaybeObserver (or subclass) instance to be applied with in a fluent manner (such as in the example above).
Since:

2.0

See Also:

DisposableMaybeObserver

Constructor Summary

Constructors
Constructor and Description

Maybe()

Constructors
Constructor and Description
`Maybe()`

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`static <T> @NonNull Maybe<T>`	`amb(@NonNull Iterable<? extends MaybeSource<? extends T>> sources)` Runs multiple MaybeSources and signals the events of the first one that signals (disposing the rest).
`static <T> @NonNull Maybe<T>`	`ambArray(MaybeSource<? extends T>... sources)` Runs multiple MaybeSources and signals the events of the first one that signals (disposing the rest).
`@NonNull Maybe<T>`	`ambWith(@NonNull MaybeSource<? extends T> other)` Mirrors the MaybeSource (current or provided) that first signals an event.
`T`	`blockingGet()` Waits in a blocking fashion until the current Maybe signals a success value (which is returned), null if completed or an exception (which is propagated).
`T`	`blockingGet(T defaultValue)` Waits in a blocking fashion until the current Maybe signals a success value (which is returned), defaultValue if completed or an exception (which is propagated).
`@NonNull Maybe<T>`	`cache()` Returns a Maybe that subscribes to this Maybe lazily, caches its event and replays it, to all the downstream subscribers.
`<U> @NonNull Maybe<U>`	`cast(@NonNull Class<? extends U> clazz)` Casts the success value of the current Maybe into the target type or signals a ClassCastException if not compatible.
`<R> @NonNull Maybe<R>`	`compose(@NonNull MaybeTransformer<? super T,? extends R> transformer)` Transform a Maybe by applying a particular Transformer function to it.
`static <T> @NonNull Flowable<T>`	`concat(@NonNull Iterable<? extends MaybeSource<? extends T>> sources)` Concatenate the single values, in a non-overlapping fashion, of the MaybeSource sources provided by an Iterable sequence.
`static <T> @NonNull Flowable<T>`	`concat(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2)` Returns a Flowable that emits the items emitted by two MaybeSources, one after the other.
`static <T> @NonNull Flowable<T>`	`concat(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2, @NonNull MaybeSource<? extends T> source3)` Returns a Flowable that emits the items emitted by three MaybeSources, one after the other.
`static <T> @NonNull Flowable<T>`	`concat(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2, @NonNull MaybeSource<? extends T> source3, @NonNull MaybeSource<? extends T> source4)` Returns a Flowable that emits the items emitted by four MaybeSources, one after the other.
`static <T> @NonNull Flowable<T>`	`concat(@NonNull Publisher<? extends MaybeSource<? extends T>> sources)` Concatenate the single values, in a non-overlapping fashion, of the MaybeSource sources provided by a Publisher sequence.
`static <T> @NonNull Flowable<T>`	`concat(@NonNull Publisher<? extends MaybeSource<? extends T>> sources, int prefetch)` Concatenate the single values, in a non-overlapping fashion, of the MaybeSource sources provided by a Publisher sequence.
`static <T> @NonNull Flowable<T>`	`concatArray(MaybeSource<? extends T>... sources)` Concatenate the single values, in a non-overlapping fashion, of the MaybeSource sources in the array.
`static <T> @NonNull Flowable<T>`	`concatArrayDelayError(MaybeSource<? extends T>... sources)` Concatenates a variable number of MaybeSource sources and delays errors from any of them till all terminate.
`static <T> @NonNull Flowable<T>`	`concatArrayEager(MaybeSource<? extends T>... sources)` Concatenates a sequence of MaybeSource eagerly into a single stream of values.
`static <T> @NonNull Flowable<T>`	`concatDelayError(@NonNull Iterable<? extends MaybeSource<? extends T>> sources)` Concatenates the Iterable sequence of MaybeSources into a single sequence by subscribing to each MaybeSource, one after the other, one at a time and delays any errors till the all inner MaybeSources terminate.
`static <T> @NonNull Flowable<T>`	`concatDelayError(@NonNull Publisher<? extends MaybeSource<? extends T>> sources)` Concatenates the Publisher sequence of Publishers into a single sequence by subscribing to each inner Publisher, one after the other, one at a time and delays any errors till the all inner and the outer Publishers terminate.
`static <T> @NonNull Flowable<T>`	`concatEager(@NonNull Iterable<? extends MaybeSource<? extends T>> sources)` Concatenates a sequence of MaybeSources eagerly into a single stream of values.
`static <T> @NonNull Flowable<T>`	`concatEager(@NonNull Publisher<? extends MaybeSource<? extends T>> sources)` Concatenates a Publisher sequence of MaybeSources eagerly into a single stream of values.
`<R> @NonNull Maybe<R>`	`concatMap(@NonNull Function<? super T,? extends MaybeSource<? extends R>> mapper)` Returns a Maybe that is based on applying a specified function to the item emitted by the source Maybe, where that function returns a MaybeSource.
`@NonNull Flowable<T>`	`concatWith(@NonNull MaybeSource<? extends T> other)` Returns a Flowable that emits the items emitted from the current MaybeSource, then the next, one after the other, without interleaving them.
`@NonNull Single<Boolean>`	`contains(@NonNull Object item)` Returns a Single that emits a Boolean that indicates whether the source Maybe emitted a specified item.
`@NonNull Single<Long>`	`count()` Returns a Single that counts the total number of items emitted (0 or 1) by the source Maybe and emits this count as a 64-bit Long.
`static <T> @NonNull Maybe<T>`	`create(@NonNull MaybeOnSubscribe<T> onSubscribe)` Provides an API (via a cold Maybe) that bridges the reactive world with the callback-style world.
`@NonNull Single<T>`	`defaultIfEmpty(T defaultItem)` Returns a Single that emits the item emitted by the source Maybe or a specified default item if the source Maybe is empty.
`static <T> @NonNull Maybe<T>`	`defer(@NonNull Supplier<? extends MaybeSource<? extends T>> maybeSupplier)` Calls a Supplier for each individual MaybeObserver to return the actual MaybeSource source to be subscribed to.
`@NonNull Maybe<T>`	`delay(long delay, @NonNull TimeUnit unit)` Returns a Maybe that signals the events emitted by the source Maybe shifted forward in time by a specified delay.
`@NonNull Maybe<T>`	`delay(long delay, @NonNull TimeUnit unit, @NonNull Scheduler scheduler)` Returns a Maybe that signals the events emitted by the source Maybe shifted forward in time by a specified delay running on the specified Scheduler.
`<U> @NonNull Maybe<T>`	`delay(@NonNull Publisher<U> delayIndicator)` Delays the emission of this Maybe until the given Publisher signals an item or completes.
`@NonNull Maybe<T>`	`delaySubscription(long delay, @NonNull TimeUnit unit)` Returns a Maybe that delays the subscription to the source Maybe by a given amount of time.
`@NonNull Maybe<T>`	`delaySubscription(long delay, @NonNull TimeUnit unit, @NonNull Scheduler scheduler)` Returns a Maybe that delays the subscription to the source Maybe by a given amount of time, both waiting and subscribing on a given Scheduler.
`<U> @NonNull Maybe<T>`	`delaySubscription(@NonNull Publisher<U> subscriptionIndicator)` Returns a Maybe that delays the subscription to this Maybe until the other Publisher emits an element or completes normally.
`@NonNull Maybe<T>`	`doAfterSuccess(@NonNull Consumer<? super T> onAfterSuccess)` Calls the specified consumer with the success item after this item has been emitted to the downstream.
`@NonNull Maybe<T>`	`doAfterTerminate(@NonNull Action onAfterTerminate)` Registers an `Action` to be called when this Maybe invokes either `onSuccess`, `onComplete` or `onError`.
`@NonNull Maybe<T>`	`doFinally(@NonNull Action onFinally)` Calls the specified action after this Maybe signals onSuccess, onError or onComplete or gets disposed by the downstream.
`@NonNull Maybe<T>`	`doOnComplete(@NonNull Action onComplete)` Modifies the source Maybe so that it invokes an action when it calls `onComplete`.
`@NonNull Maybe<T>`	`doOnDispose(@NonNull Action onDispose)` Calls the shared `Action` if a MaybeObserver subscribed to the current Maybe disposes the common Disposable it received via onSubscribe.
`@NonNull Maybe<T>`	`doOnError(@NonNull Consumer<? super Throwable> onError)` Calls the shared consumer with the error sent via onError for each MaybeObserver that subscribes to the current Maybe.
`@NonNull Maybe<T>`	`doOnEvent(@NonNull BiConsumer<? super T,? super Throwable> onEvent)` Calls the given onEvent callback with the (success value, null) for an onSuccess, (null, throwable) for an onError or (null, null) for an onComplete signal from this Maybe before delivering said signal to the downstream.
`@NonNull Maybe<T>`	`doOnSubscribe(@NonNull Consumer<? super Disposable> onSubscribe)` Calls the shared consumer with the Disposable sent through the onSubscribe for each MaybeObserver that subscribes to the current Maybe.
`@NonNull Maybe<T>`	`doOnSuccess(@NonNull Consumer<? super T> onSuccess)` Calls the shared consumer with the success value sent via onSuccess for each MaybeObserver that subscribes to the current Maybe.
`@NonNull Maybe<T>`	`doOnTerminate(@NonNull Action onTerminate)` Returns a Maybe instance that calls the given onTerminate callback just before this Maybe completes normally or with an exception.
`static <T> @NonNull Maybe<T>`	`empty()` Returns a (singleton) Maybe instance that calls `onComplete` immediately.
`static <T> @NonNull Maybe<T>`	`error(@NonNull Supplier<? extends Throwable> supplier)` Returns a Maybe that invokes a `MaybeObserver`'s `onError` method when the MaybeObserver subscribes to it.
`static <T> @NonNull Maybe<T>`	`error(@NonNull Throwable exception)` Returns a Maybe that invokes a subscriber's `onError` method when the subscriber subscribes to it.
`@NonNull Maybe<T>`	`filter(@NonNull Predicate<? super T> predicate)` Filters the success item of the Maybe via a predicate function and emitting it if the predicate returns true, completing otherwise.
`<R> @NonNull Maybe<R>`	`flatMap(@NonNull Function<? super T,? extends MaybeSource<? extends R>> mapper)` Returns a Maybe that is based on applying a specified function to the item emitted by the source Maybe, where that function returns a MaybeSource.
`<R> @NonNull Maybe<R>`	`flatMap(@NonNull Function<? super T,? extends MaybeSource<? extends R>> onSuccessMapper, @NonNull Function<? super Throwable,? extends MaybeSource<? extends R>> onErrorMapper, @NonNull Supplier<? extends MaybeSource<? extends R>> onCompleteSupplier)` Maps the onSuccess, onError or onComplete signals of this Maybe into MaybeSource and emits that MaybeSource's signals.
`<U,R> @NonNull Maybe<R>`	`flatMap(@NonNull Function<? super T,? extends MaybeSource<? extends U>> mapper, @NonNull BiFunction<? super T,? super U,? extends R> resultSelector)` Returns a Maybe that emits the results of a specified function to the pair of values emitted by the source Maybe and a specified mapped MaybeSource.
`@NonNull Completable`	`flatMapCompletable(@NonNull Function<? super T,? extends CompletableSource> mapper)` Returns a `Completable` that completes based on applying a specified function to the item emitted by the source `Maybe`, where that function returns a `Completable`.
`<R> @NonNull Observable<R>`	`flatMapObservable(@NonNull Function<? super T,? extends ObservableSource<? extends R>> mapper)` Returns an Observable that is based on applying a specified function to the item emitted by the source Maybe, where that function returns an ObservableSource.
`<R> @NonNull Flowable<R>`	`flatMapPublisher(@NonNull Function<? super T,? extends Publisher<? extends R>> mapper)` Returns a Flowable that emits items based on applying a specified function to the item emitted by the source Maybe, where that function returns a Publisher.
`<R> @NonNull Single<R>`	`flatMapSingle(@NonNull Function<? super T,? extends SingleSource<? extends R>> mapper)` Returns a `Single` based on applying a specified function to the item emitted by the source `Maybe`, where that function returns a `Single`.
`<R> @NonNull Maybe<R>`	`flatMapSingleElement(@NonNull Function<? super T,? extends SingleSource<? extends R>> mapper)` Returns a `Maybe` based on applying a specified function to the item emitted by the source `Maybe`, where that function returns a `Single`.
`<U> @NonNull Flowable<U>`	`flattenAsFlowable(@NonNull Function<? super T,? extends Iterable<? extends U>> mapper)` Maps the success value of the upstream `Maybe` into an `Iterable` and emits its items as a `Flowable` sequence.
`<U> @NonNull Observable<U>`	`flattenAsObservable(@NonNull Function<? super T,? extends Iterable<? extends U>> mapper)` Maps the success value of the upstream `Maybe` into an `Iterable` and emits its items as an `Observable` sequence.
`<R> @NonNull Flowable<R>`	`flattenStreamAsFlowable(@NonNull Function<? super T,? extends Stream<? extends R>> mapper)` Maps the upstream succecss value into a Java `Stream` and emits its items to the downstream consumer as a `Flowable`.
`<R> @NonNull Observable<R>`	`flattenStreamAsObservable(@NonNull Function<? super T,? extends Stream<? extends R>> mapper)` Maps the upstream succecss value into a Java `Stream` and emits its items to the downstream consumer as an `Observable`.
`static <T> @NonNull Maybe<T>`	`fromAction(@NonNull Action run)` Returns a Maybe instance that runs the given Action for each subscriber and emits either its exception or simply completes.
`static <T> @NonNull Maybe<T>`	`fromCallable(@NonNull Callable<? extends T> callable)` Returns a `Maybe` that invokes the given `Callable` for each individual `MaybeObserver` that subscribes and emits the resulting non-null item via `onSuccess` while considering a `null` result from the `Callable` as indication for valueless completion via `onComplete`.
`static <T> @NonNull Maybe<T>`	`fromCompletable(@NonNull CompletableSource completableSource)` Wraps a CompletableSource into a Maybe.
`static <T> @NonNull Maybe<T>`	`fromCompletionStage(@NonNull CompletionStage<T> stage)` Signals the completion value or error of the given (hot) `CompletionStage`-based asynchronous calculation.
`static <T> @NonNull Maybe<T>`	`fromFuture(@NonNull Future<? extends T> future)` Converts a `Future` into a Maybe, treating a null result as an indication of emptiness.
`static <T> @NonNull Maybe<T>`	`fromFuture(@NonNull Future<? extends T> future, long timeout, @NonNull TimeUnit unit)` Converts a `Future` into a Maybe, with a timeout on the Future.
`static <T> @NonNull Maybe<T>`	`fromOptional(@NonNull Optional<T> optional)` Converts the existing value of the provided optional into a `just(Object)` or an empty optional into an `empty()` `Maybe` instance.
`static <T> @NonNull Maybe<T>`	`fromRunnable(@NonNull Runnable run)` Returns a Maybe instance that runs the given Action for each subscriber and emits either its exception or simply completes.
`static <T> @NonNull Maybe<T>`	`fromSingle(@NonNull SingleSource<T> singleSource)` Wraps a SingleSource into a Maybe.
`static <T> @NonNull Maybe<T>`	`fromSupplier(@NonNull Supplier<? extends T> supplier)` Returns a `Maybe` that invokes the given `Supplier` for each individual `MaybeObserver` that subscribes and emits the resulting non-null item via `onSuccess` while considering a `null` result from the `Supplier` as indication for valueless completion via `onComplete`.
`@NonNull Maybe<T>`	`hide()` Hides the identity of this Maybe and its Disposable.
`@NonNull Completable`	`ignoreElement()` Ignores the item emitted by the source Maybe and only calls `onComplete` or `onError`.
`@NonNull Single<Boolean>`	`isEmpty()` Returns a Single that emits `true` if the source Maybe is empty, otherwise `false`.
`static <T> @NonNull Maybe<T>`	`just(T item)` Returns a `Maybe` that emits a specified item.
`<R> @NonNull Maybe<R>`	`lift(@NonNull MaybeOperator<? extends R,? super T> lift)` This method requires advanced knowledge about building operators, please consider other standard composition methods first; Returns a `Maybe` which, when subscribed to, invokes the `apply(MaybeObserver)` method of the provided `MaybeOperator` for each individual downstream `Maybe` and allows the insertion of a custom operator by accessing the downstream's `MaybeObserver` during this subscription phase and providing a new `MaybeObserver`, containing the custom operator's intended business logic, that will be used in the subscription process going further upstream.
`<R> @NonNull Maybe<R>`	`map(@NonNull Function<? super T,? extends R> mapper)` Returns a Maybe that applies a specified function to the item emitted by the source Maybe and emits the result of this function application.
`<R> @NonNull Maybe<R>`	`mapOptional(@NonNull Function<? super T,Optional<? extends R>> mapper)` Maps the upstream success value into an `Optional` and emits the contained item if not empty.
`@NonNull Single<Notification<T>>`	`materialize()` Maps the signal types of this Maybe into a `Notification` of the same kind and emits it as a single success value to downstream.
`static <T> @NonNull Flowable<T>`	`merge(@NonNull Iterable<? extends MaybeSource<? extends T>> sources)` Merges an Iterable sequence of MaybeSource instances into a single Flowable sequence, running all MaybeSources at once.
`static <T> @NonNull Maybe<T>`	`merge(@NonNull MaybeSource<? extends MaybeSource<? extends T>> source)` Flattens a `MaybeSource` that emits a `MaybeSource` into a single `MaybeSource` that emits the item emitted by the nested `MaybeSource`, without any transformation.
`static <T> @NonNull Flowable<T>`	`merge(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2)` Flattens two MaybeSources into a single Flowable, without any transformation.
`static <T> @NonNull Flowable<T>`	`merge(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2, @NonNull MaybeSource<? extends T> source3)` Flattens three MaybeSources into a single Flowable, without any transformation.
`static <T> @NonNull Flowable<T>`	`merge(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2, @NonNull MaybeSource<? extends T> source3, @NonNull MaybeSource<? extends T> source4)` Flattens four MaybeSources into a single Flowable, without any transformation.
`static <T> @NonNull Flowable<T>`	`merge(@NonNull Publisher<? extends MaybeSource<? extends T>> sources)` Merges a Flowable sequence of MaybeSource instances into a single Flowable sequence, running all MaybeSources at once.
`static <T> @NonNull Flowable<T>`	`merge(@NonNull Publisher<? extends MaybeSource<? extends T>> sources, int maxConcurrency)` Merges a Flowable sequence of MaybeSource instances into a single Flowable sequence, running at most maxConcurrency MaybeSources at once.
`static <T> @NonNull Flowable<T>`	`mergeArray(MaybeSource<? extends T>... sources)` Merges an array sequence of MaybeSource instances into a single Flowable sequence, running all MaybeSources at once.
`static <T> @NonNull Flowable<T>`	`mergeArrayDelayError(MaybeSource<? extends T>... sources)` Flattens an array of MaybeSources into one Flowable, in a way that allows a Subscriber to receive all successfully emitted items from each of the source MaybeSources without being interrupted by an error notification from one of them.
`static <T> @NonNull Flowable<T>`	`mergeDelayError(@NonNull Iterable<? extends MaybeSource<? extends T>> sources)` Flattens an Iterable of MaybeSources into one Flowable, in a way that allows a Subscriber to receive all successfully emitted items from each of the source MaybeSources without being interrupted by an error notification from one of them.
`static <T> @NonNull Flowable<T>`	`mergeDelayError(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2)` Flattens two MaybeSources into one Flowable, in a way that allows a Subscriber to receive all successfully emitted items from each of the source MaybeSources without being interrupted by an error notification from one of them.
`static <T> @NonNull Flowable<T>`	`mergeDelayError(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2, @NonNull MaybeSource<? extends T> source3)` Flattens three MaybeSource into one Flowable, in a way that allows a Subscriber to receive all successfully emitted items from all of the source MaybeSources without being interrupted by an error notification from one of them.
`static <T> @NonNull Flowable<T>`	`mergeDelayError(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2, @NonNull MaybeSource<? extends T> source3, @NonNull MaybeSource<? extends T> source4)` Flattens four MaybeSources into one Flowable, in a way that allows a Subscriber to receive all successfully emitted items from all of the source MaybeSources without being interrupted by an error notification from one of them.
`static <T> @NonNull Flowable<T>`	`mergeDelayError(@NonNull Publisher<? extends MaybeSource<? extends T>> sources)` Flattens a Publisher that emits MaybeSources into one Publisher, in a way that allows a Subscriber to receive all successfully emitted items from all of the source MaybeSources without being interrupted by an error notification from one of them or even the main Publisher.
`static <T> @NonNull Flowable<T>`	`mergeDelayError(@NonNull Publisher<? extends MaybeSource<? extends T>> sources, int maxConcurrency)` Flattens a Publisher that emits MaybeSources into one Publisher, in a way that allows a Subscriber to receive all successfully emitted items from all of the source MaybeSources without being interrupted by an error notification from one of them or even the main Publisher as well as limiting the total number of active MaybeSources.
`@NonNull Flowable<T>`	`mergeWith(@NonNull MaybeSource<? extends T> other)` Flattens this and another Maybe into a single Flowable, without any transformation.
`static <T> @NonNull Maybe<T>`	`never()` Returns a Maybe that never sends any items or notifications to a `MaybeObserver`.
`@NonNull Maybe<T>`	`observeOn(@NonNull Scheduler scheduler)` Wraps a Maybe to emit its item (or notify of its error) on a specified `Scheduler`, asynchronously.
`<U> @NonNull Maybe<U>`	`ofType(@NonNull Class<U> clazz)` Filters the items emitted by a Maybe, only emitting its success value if that is an instance of the supplied Class.
`@NonNull Maybe<T>`	`onErrorComplete()` Returns a Maybe instance that if this Maybe emits an error, it will emit an onComplete and swallow the throwable.
`@NonNull Maybe<T>`	`onErrorComplete(@NonNull Predicate<? super Throwable> predicate)` Returns a Maybe instance that if this Maybe emits an error and the predicate returns true, it will emit an onComplete and swallow the throwable.
`@NonNull Maybe<T>`	`onErrorResumeNext(@NonNull Function<? super Throwable,? extends MaybeSource<? extends T>> resumeFunction)` Instructs a Maybe to pass control to another Maybe rather than invoking `onError` if it encounters an error.
`@NonNull Maybe<T>`	`onErrorResumeWith(@NonNull MaybeSource<? extends T> next)` Instructs a Maybe to pass control to another `MaybeSource` rather than invoking `onError` if it encounters an error.
`@NonNull Maybe<T>`	`onErrorReturn(@NonNull Function<? super Throwable,? extends T> valueSupplier)` Instructs a Maybe to emit an item (returned by a specified function) rather than invoking `onError` if it encounters an error.
`@NonNull Maybe<T>`	`onErrorReturnItem(T item)` Instructs a Maybe to emit an item (returned by a specified function) rather than invoking `onError` if it encounters an error.
`@NonNull Maybe<T>`	`onExceptionResumeNext(@NonNull MaybeSource<? extends T> next)` Instructs a Maybe to pass control to another MaybeSource rather than invoking `onError` if it encounters an `Exception`.
`@NonNull Maybe<T>`	`onTerminateDetach()` Nulls out references to the upstream producer and downstream MaybeObserver if the sequence is terminated or downstream calls dispose().
`@NonNull Flowable<T>`	`repeat()` Returns a Flowable that repeats the sequence of items emitted by the source Maybe indefinitely.
`@NonNull Flowable<T>`	`repeat(long times)` Returns a Flowable that repeats the sequence of items emitted by the source Maybe at most `count` times.
`@NonNull Flowable<T>`	`repeatUntil(@NonNull BooleanSupplier stop)` Returns a Flowable that repeats the sequence of items emitted by the source Maybe until the provided stop function returns true.
`@NonNull Flowable<T>`	`repeatWhen(@NonNull Function<? super Flowable<Object>,? extends Publisher<?>> handler)` Returns a Flowable that emits the same values as the source Publisher with the exception of an `onComplete`.
`@NonNull Maybe<T>`	`retry()` Returns a Maybe that mirrors the source Maybe, resubscribing to it if it calls `onError` (infinite retry count).
`@NonNull Maybe<T>`	`retry(@NonNull BiPredicate<? super Integer,? super Throwable> predicate)` Returns a Maybe that mirrors the source Maybe, resubscribing to it if it calls `onError` and the predicate returns true for that specific exception and retry count.
`@NonNull Maybe<T>`	`retry(long count)` Returns a Maybe that mirrors the source Maybe, resubscribing to it if it calls `onError` up to a specified number of retries.
`@NonNull Maybe<T>`	`retry(long times, @NonNull Predicate<? super Throwable> predicate)` Retries at most times or until the predicate returns false, whichever happens first.
`@NonNull Maybe<T>`	`retry(@NonNull Predicate<? super Throwable> predicate)` Retries the current Maybe if it fails and the predicate returns true.
`@NonNull Maybe<T>`	`retryUntil(@NonNull BooleanSupplier stop)` Retries until the given stop function returns true.
`@NonNull Maybe<T>`	`retryWhen(@NonNull Function<? super Flowable<Throwable>,? extends Publisher<?>> handler)` Returns a Maybe that emits the same values as the source Maybe with the exception of an `onError`.
`static <T> @NonNull Single<Boolean>`	`sequenceEqual(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2)` Returns a Single that emits a Boolean value that indicates whether two MaybeSource sequences are the same by comparing the items emitted by each MaybeSource pairwise.
`static <T> @NonNull Single<Boolean>`	`sequenceEqual(@NonNull MaybeSource<? extends T> source1, @NonNull MaybeSource<? extends T> source2, @NonNull BiPredicate<? super T,? super T> isEqual)` Returns a Single that emits a Boolean value that indicates whether two MaybeSources are the same by comparing the items emitted by each MaybeSource pairwise based on the results of a specified equality function.
`@NonNull Disposable`	`subscribe()` Subscribes to a Maybe and ignores `onSuccess` and `onComplete` emissions.
`@NonNull Disposable`	`subscribe(@NonNull Consumer<? super T> onSuccess)` Subscribes to a Maybe and provides a callback to handle the items it emits.
`@NonNull Disposable`	`subscribe(@NonNull Consumer<? super T> onSuccess, @NonNull Consumer<? super Throwable> onError)` Subscribes to a Maybe and provides callbacks to handle the items it emits and any error notification it issues.
`@NonNull Disposable`	`subscribe(@NonNull Consumer<? super T> onSuccess, @NonNull Consumer<? super Throwable> onError, @NonNull Action onComplete)` Subscribes to a Maybe and provides callbacks to handle the items it emits and any error or completion notification it issues.
`void`	`subscribe(@NonNull MaybeObserver<? super T> observer)` Subscribes the given `MaybeObserver` to this `MaybeSource` instance.
`protected abstract void`	`subscribeActual(@NonNull MaybeObserver<? super T> observer)` Implement this method in subclasses to handle the incoming `MaybeObserver`s.
`@NonNull Maybe<T>`	`subscribeOn(@NonNull Scheduler scheduler)` Asynchronously subscribes subscribers to this Maybe on the specified `Scheduler`.
`<E extends MaybeObserver<? super T>> E`	`subscribeWith(E observer)` Subscribes a given MaybeObserver (subclass) to this Maybe and returns the given MaybeObserver as is.
`@NonNull Maybe<T>`	`switchIfEmpty(@NonNull MaybeSource<? extends T> other)` Returns a Maybe that emits the items emitted by the source Maybe or the items of an alternate MaybeSource if the current Maybe is empty.
`@NonNull Single<T>`	`switchIfEmpty(@NonNull SingleSource<? extends T> other)` Returns a Single that emits the items emitted by the source Maybe or the item of an alternate SingleSource if the current Maybe is empty.
`<U> @NonNull Maybe<T>`	`takeUntil(@NonNull MaybeSource<U> other)` Returns a Maybe that emits the items emitted by the source Maybe until a second MaybeSource emits an item.
`<U> @NonNull Maybe<T>`	`takeUntil(@NonNull Publisher<U> other)` Returns a Maybe that emits the item emitted by the source Maybe until a second Publisher emits an item.
`@NonNull TestObserver<T>`	`test()` Creates a TestObserver and subscribes it to this Maybe.
`@NonNull TestObserver<T>`	`test(boolean dispose)` Creates a TestObserver optionally in cancelled state, then subscribes it to this Maybe.
`@NonNull Maybe<T>`	`timeout(long timeout, @NonNull TimeUnit timeUnit)` Returns a Maybe that mirrors the source Maybe but applies a timeout policy for each emitted item.
`@NonNull Maybe<T>`	`timeout(long timeout, @NonNull TimeUnit timeUnit, @NonNull MaybeSource<? extends T> fallback)` Returns a Maybe that mirrors the source Maybe but applies a timeout policy for each emitted item.
`@NonNull Maybe<T>`	`timeout(long timeout, @NonNull TimeUnit timeUnit, @NonNull Scheduler scheduler)` Returns a Maybe that mirrors the source Maybe but applies a timeout policy for each emitted item, where this policy is governed on a specified Scheduler.
`@NonNull Maybe<T>`	`timeout(long timeout, @NonNull TimeUnit timeUnit, @NonNull Scheduler scheduler, @NonNull MaybeSource<? extends T> fallback)` Returns a Maybe that mirrors the source Maybe but applies a timeout policy for each emitted item using a specified Scheduler.
`<U> @NonNull Maybe<T>`	`timeout(@NonNull MaybeSource<U> timeoutIndicator)` If the current `Maybe` didn't signal an event before the `timeoutIndicator` `MaybeSource` signals, a `TimeoutException` is signaled instead.
`<U> @NonNull Maybe<T>`	`timeout(@NonNull MaybeSource<U> timeoutIndicator, @NonNull MaybeSource<? extends T> fallback)` If the current `Maybe` didn't signal an event before the `timeoutIndicator` `MaybeSource` signals, the current `Maybe` is disposed and the `fallback` `MaybeSource` subscribed to as a continuation.
`<U> @NonNull Maybe<T>`	`timeout(@NonNull Publisher<U> timeoutIndicator)` If the current `Maybe` source didn't signal an event before the `timeoutIndicator` `Publisher` signals, a `TimeoutException` is signaled instead.
`<U> @NonNull Maybe<T>`	`timeout(@NonNull Publisher<U> timeoutIndicator, @NonNull MaybeSource<? extends T> fallback)` If the current `Maybe` didn't signal an event before the `timeoutIndicator` `Publisher` signals, the current `Maybe` is disposed and the `fallback` `MaybeSource` subscribed to as a continuation.
`static @NonNull Maybe<Long>`	`timer(long delay, @NonNull TimeUnit unit)` Returns a Maybe that emits `0L` after a specified delay.
`static @NonNull Maybe<Long>`	`timer(long delay, @NonNull TimeUnit unit, @NonNull Scheduler scheduler)` Returns a Maybe that emits `0L` after a specified delay on a specified Scheduler.
`<R> R`	`to(@NonNull MaybeConverter<T,? extends R> converter)` Calls the specified converter function during assembly time and returns its resulting value.
`@NonNull CompletionStage<T>`	`toCompletionStage()` Signals the upstream success item (or a `NoSuchElementException` if the upstream is empty) via a `CompletionStage`.
`@NonNull CompletionStage<T>`	`toCompletionStage(T defaultItem)` Signals the upstream success item (or the default item if the upstream is empty) via a `CompletionStage`.
`@NonNull Flowable<T>`	`toFlowable()` Converts this Maybe into a backpressure-aware Flowable instance composing cancellation through.
`@NonNull Observable<T>`	`toObservable()` Converts this Maybe into an Observable instance composing disposal through.
`@NonNull Single<T>`	`toSingle()` Converts this Maybe into a Single instance composing disposal through and turning an empty Maybe into a signal of NoSuchElementException.
`static <T> @NonNull Maybe<T>`	`unsafeCreate(@NonNull MaybeSource<T> onSubscribe)` Advanced use only: creates a Maybe instance without any safeguards by using a callback that is called with a MaybeObserver.
`@NonNull Maybe<T>`	`unsubscribeOn(@NonNull Scheduler scheduler)` Returns a Maybe which makes sure when a MaybeObserver disposes the Disposable, that call is propagated up on the specified scheduler.
`static <T,D> @NonNull Maybe<T>`	`using(@NonNull Supplier<? extends D> resourceSupplier, @NonNull Function<? super D,? extends MaybeSource<? extends T>> sourceSupplier, @NonNull Consumer<? super D> resourceDisposer)` Constructs a Maybe that creates a dependent resource object which is disposed of when the upstream terminates or the downstream calls dispose().
`static <T,D> @NonNull Maybe<T>`	`using(@NonNull Supplier<? extends D> resourceSupplier, @NonNull Function<? super D,? extends MaybeSource<? extends T>> sourceSupplier, @NonNull Consumer<? super D> resourceDisposer, boolean eager)` Constructs a Maybe that creates a dependent resource object which is disposed of just before termination if you have set `disposeEagerly` to `true` and a downstream dispose() does not occur before termination.
`static <T> @NonNull Maybe<T>`	`wrap(@NonNull MaybeSource<T> source)` Wraps a MaybeSource instance into a new Maybe instance if not already a Maybe instance.
`static <T,R> @NonNull Maybe<R>`	`zip(@NonNull Iterable<? extends MaybeSource<? extends T>> sources, @NonNull Function<? super Object[],? extends R> zipper)` Returns a Maybe that emits the results of a specified combiner function applied to combinations of items emitted, in sequence, by an Iterable of other MaybeSources.
`static <T1,T2,R> @NonNull Maybe<R>`	`zip(@NonNull MaybeSource<? extends T1> source1, @NonNull MaybeSource<? extends T2> source2, @NonNull BiFunction<? super T1,? super T2,? extends R> zipper)` Returns a Maybe that emits the results of a specified combiner function applied to combinations of two items emitted, in sequence, by two other MaybeSources.
`static <T1,T2,T3,R> @NonNull Maybe<R>`	`zip(@NonNull MaybeSource<? extends T1> source1, @NonNull MaybeSource<? extends T2> source2, @NonNull MaybeSource<? extends T3> source3, @NonNull Function3<? super T1,? super T2,? super T3,? extends R> zipper)` Returns a Maybe that emits the results of a specified combiner function applied to combinations of three items emitted, in sequence, by three other MaybeSources.
`static <T1,T2,T3,T4,R> @NonNull Maybe<R>`	`zip(@NonNull MaybeSource<? extends T1> source1, @NonNull MaybeSource<? extends T2> source2, @NonNull MaybeSource<? extends T3> source3, @NonNull MaybeSource<? extends T4> source4, @NonNull Function4<? super T1,? super T2,? super T3,? super T4,? extends R> zipper)` Returns a Maybe that emits the results of a specified combiner function applied to combinations of four items emitted, in sequence, by four other MaybeSources.
`static <T1,T2,T3,T4,T5,R> @NonNull Maybe<R>`	`zip(@NonNull MaybeSource<? extends T1> source1, @NonNull MaybeSource<? extends T2> source2, @NonNull MaybeSource<? extends T3> source3, @NonNull MaybeSource<? extends T4> source4, @NonNull MaybeSource<? extends T5> source5, @NonNull Function5<? super T1,? super T2,? super T3,? super T4,? super T5,? extends R> zipper)` Returns a Maybe that emits the results of a specified combiner function applied to combinations of five items emitted, in sequence, by five other MaybeSources.
`static <T1,T2,T3,T4,T5,T6,R> @NonNull Maybe<R>`	`zip(@NonNull MaybeSource<? extends T1> source1, @NonNull MaybeSource<? extends T2> source2, @NonNull MaybeSource<? extends T3> source3, @NonNull MaybeSource<? extends T4> source4, @NonNull MaybeSource<? extends T5> source5, @NonNull MaybeSource<? extends T6> source6, @NonNull Function6<? super T1,? super T2,? super T3,? super T4,? super T5,? super T6,? extends R> zipper)` Returns a Maybe that emits the results of a specified combiner function applied to combinations of six items emitted, in sequence, by six other MaybeSources.
`static <T1,T2,T3,T4,T5,T6,T7,R> @NonNull Maybe<R>`	`zip(@NonNull MaybeSource<? extends T1> source1, @NonNull MaybeSource<? extends T2> source2, @NonNull MaybeSource<? extends T3> source3, @NonNull MaybeSource<? extends T4> source4, @NonNull MaybeSource<? extends T5> source5, @NonNull MaybeSource<? extends T6> source6, @NonNull MaybeSource<? extends T7> source7, @NonNull Function7<? super T1,? super T2,? super T3,? super T4,? super T5,? super T6,? super T7,? extends R> zipper)` Returns a Maybe that emits the results of a specified combiner function applied to combinations of seven items emitted, in sequence, by seven other MaybeSources.
`static <T1,T2,T3,T4,T5,T6,T7,T8,R> @NonNull Maybe<R>`	`zip(@NonNull MaybeSource<? extends T1> source1, @NonNull MaybeSource<? extends T2> source2, @NonNull MaybeSource<? extends T3> source3, @NonNull MaybeSource<? extends T4> source4, @NonNull MaybeSource<? extends T5> source5, @NonNull MaybeSource<? extends T6> source6, @NonNull MaybeSource<? extends T7> source7, @NonNull MaybeSource<? extends T8> source8, @NonNull Function8<? super T1,? super T2,? super T3,? super T4,? super T5,? super T6,? super T7,? super T8,? extends R> zipper)` Returns a Maybe that emits the results of a specified combiner function applied to combinations of eight items emitted, in sequence, by eight other MaybeSources.
`static <T1,T2,T3,T4,T5,T6,T7,T8,T9,R> @NonNull Maybe<R>`	zip(@NonNull MaybeSource<? extends T1> source1, @NonNull MaybeSource<? extends T2> source2, @NonNull MaybeSource<? extends T3> source3, @NonNull MaybeSource<? extends T4> source4, @NonNull MaybeSource<? extends T5> source5, @NonNull MaybeSource<? extends T6> source6, @NonNull MaybeSource<? extends T7> source7, @NonNull MaybeSource<? extends T8> source8, @NonNull MaybeSource<? extends T9> source9, @NonNull Function9<? super T1,? super T2,? super T3,? super T4,? super T5,? super T6,? super T7,? super T8,? super T9,? extends R> zipper) Returns a Maybe that emits the results of a specified combiner function applied to combinations of nine items emitted, in sequence, by nine other MaybeSources.
`static <T,R> @NonNull Maybe<R>`	`zipArray(@NonNull Function<? super Object[],? extends R> zipper, MaybeSource<? extends T>... sources)` Returns a Maybe that emits the results of a specified combiner function applied to combinations of items emitted, in sequence, by an array of other MaybeSources.
`<U,R> @NonNull Maybe<R>`	`zipWith(@NonNull MaybeSource<? extends U> other, @NonNull BiFunction<? super T,? super U,? extends R> zipper)` Waits until this and the other MaybeSource signal a success value then applies the given BiFunction to those values and emits the BiFunction's resulting value to downstream.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
 - Maybe
```
public Maybe()
```
- Method Detail
 - amb
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Maybe<T> amb(@NonNull @NonNull Iterable<? extends MaybeSource<? extends T>> sources)
```
 Runs multiple MaybeSources and signals the events of the first one that signals (disposing the rest).
 
 Scheduler:
 
 amb does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the value type
 
 Parameters:
 
 sources - the Iterable sequence of sources. A subscription to each source will occur in the same order as in the Iterable.
 
 Returns:
 
 the new Maybe instance
 - ambArray
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
 @SafeVarargs
public static <T> @NonNull Maybe<T> ambArray(@NonNull MaybeSource<? extends T>... sources)
```
 Runs multiple MaybeSources and signals the events of the first one that signals (disposing the rest).
 
 Scheduler:
 
 ambArray does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the value type
 
 Parameters:
 
 sources - the array of sources. A subscription to each source will occur in the same order as in the array.
 
 Returns:
 
 the new Maybe instance
 - concat
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Flowable<T> concat(@NonNull @NonNull Iterable<? extends MaybeSource<? extends T>> sources)
```
 Concatenate the single values, in a non-overlapping fashion, of the MaybeSource sources provided by an Iterable sequence.
 
 Backpressure:
 
 The returned Flowable honors the backpressure of the downstream consumer.
 
 Scheduler:
 
 concat does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the value type
 
 Parameters:
 
 sources - the Iterable sequence of MaybeSource instances
 
 Returns:
 
 the new Flowable instance
 - concat
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Flowable<T> concat(@NonNull @NonNull MaybeSource<? extends T> source1,
 @NonNull @NonNull MaybeSource<? extends T> source2)
```
 Returns a Flowable that emits the items emitted by two MaybeSources, one after the other.
 
 Backpressure:
 
 The returned Flowable honors the backpressure of the downstream consumer.
 
 Scheduler:
 
 concat does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the common value type
 
 Parameters:
 
 source1 - a MaybeSource to be concatenated
 
 source2 - a MaybeSource to be concatenated
 
 Returns:
 
 a Flowable that emits items emitted by the two source MaybeSources, one after the other.
 
 See Also:
 
 ReactiveX operators documentation: Concat
 - concat
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Flowable<T> concat(@NonNull @NonNull MaybeSource<? extends T> source1,
 @NonNull @NonNull MaybeSource<? extends T> source2,
 @NonNull @NonNull MaybeSource<? extends T> source3)
```
 Returns a Flowable that emits the items emitted by three MaybeSources, one after the other.
 
 Backpressure:
 
 The returned Flowable honors the backpressure of the downstream consumer.
 
 Scheduler:
 
 concat does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the common value type
 
 Parameters:
 
 source1 - a MaybeSource to be concatenated
 
 source2 - a MaybeSource to be concatenated
 
 source3 - a MaybeSource to be concatenated
 
 Returns:
 
 a Flowable that emits items emitted by the three source MaybeSources, one after the other.
 
 See Also:
 
 ReactiveX operators documentation: Concat
 - concat
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Flowable<T> concat(@NonNull @NonNull MaybeSource<? extends T> source1,
 @NonNull @NonNull MaybeSource<? extends T> source2,
 @NonNull @NonNull MaybeSource<? extends T> source3,
 @NonNull @NonNull MaybeSource<? extends T> source4)
```
 Returns a Flowable that emits the items emitted by four MaybeSources, one after the other.
 
 Backpressure:
 
 The returned Flowable honors the backpressure of the downstream consumer.
 
 Scheduler:
 
 concat does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the common value type
 
 Parameters:
 
 source1 - a MaybeSource to be concatenated
 
 source2 - a MaybeSource to be concatenated
 
 source3 - a MaybeSource to be concatenated
 
 source4 - a MaybeSource to be concatenated
 
 Returns:
 
 a Flowable that emits items emitted by the four source MaybeSources, one after the other.
 
 See Also:
 
 ReactiveX operators documentation: Concat
 - concat
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public static <T> @NonNull Flowable<T> concat(@NonNull @NonNull Publisher<? extends MaybeSource<? extends T>> sources)
```
 Concatenate the single values, in a non-overlapping fashion, of the MaybeSource sources provided by a Publisher sequence.
 
 Backpressure:
 
 The returned Flowable honors the backpressure of the downstream consumer and expects the Publisher to honor backpressure as well. If the sources Publisher violates this, a MissingBackpressureException is signalled.
 
 Scheduler:
 
 concat does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the value type
 
 Parameters:
 
 sources - the Publisher of MaybeSource instances
 
 Returns:
 
 the new Flowable instance
 - concat
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Flowable<T> concat(@NonNull @NonNull Publisher<? extends MaybeSource<? extends T>> sources,
 int prefetch)
```
 Concatenate the single values, in a non-overlapping fashion, of the MaybeSource sources provided by a Publisher sequence.
 
 Backpressure:
 
 The returned Flowable honors the backpressure of the downstream consumer and expects the Publisher to honor backpressure as well. If the sources Publisher violates this, a MissingBackpressureException is signalled.
 
 Scheduler:
 
 concat does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the value type
 
 Parameters:
 
 sources - the Publisher of MaybeSource instances
 
 prefetch - the number of MaybeSources to prefetch from the Publisher
 
 Returns:
 
 the new Flowable instance
 - concatArray
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
 @SafeVarargs
public static <T> @NonNull Flowable<T> concatArray(@NonNull MaybeSource<? extends T>... sources)
```
 Concatenate the single values, in a non-overlapping fashion, of the MaybeSource sources in the array.
 
 Backpressure:
 
 The returned Flowable honors the backpressure of the downstream consumer.
 
 Scheduler:
 
 concatArray does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the value type
 
 Parameters:
 
 sources - the array of MaybeSource instances
 
 Returns:
 
 the new Flowable instance
 - concatArrayDelayError
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @SchedulerSupport(value="none")
 @SafeVarargs
 @NonNull
public static <T> @NonNull Flowable<T> concatArrayDelayError(@NonNull MaybeSource<? extends T>... sources)
```
 Concatenates a variable number of MaybeSource sources and delays errors from any of them till all terminate.
 
 Backpressure:
 
 The operator honors backpressure from downstream.
 
 Scheduler:
 
 concatArrayDelayError does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the common base value type
 
 Parameters:
 
 sources - the array of sources
 
 Returns:
 
 the new Flowable instance
 
 Throws:
 
 NullPointerException - if sources is null
 - concatArrayEager
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
 @SafeVarargs
public static <T> @NonNull Flowable<T> concatArrayEager(@NonNull MaybeSource<? extends T>... sources)
```
 Concatenates a sequence of MaybeSource eagerly into a single stream of values.
 Eager concatenation means that once a subscriber subscribes, this operator subscribes to all of the source MaybeSources. The operator buffers the value emitted by these MaybeSources and then drains them in order, each one after the previous one completes.
 
 Backpressure:
 
 The operator honors backpressure from downstream.
 
 Scheduler:
 
 This method does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the value type
 
 Parameters:
 
 sources - a sequence of MaybeSources that need to be eagerly concatenated
 
 Returns:
 
 the new Flowable instance with the specified concatenation behavior
 - concatDelayError
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Flowable<T> concatDelayError(@NonNull @NonNull Iterable<? extends MaybeSource<? extends T>> sources)
```
 Concatenates the Iterable sequence of MaybeSources into a single sequence by subscribing to each MaybeSource, one after the other, one at a time and delays any errors till the all inner MaybeSources terminate.
 
 Backpressure:
 
 The operator honors backpressure from downstream.
 
 Scheduler:
 
 concatDelayError does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the common element base type
 
 Parameters:
 
 sources - the Iterable sequence of MaybeSources
 
 Returns:
 
 the new Flowable with the concatenating behavior
 - concatDelayError
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public static <T> @NonNull Flowable<T> concatDelayError(@NonNull @NonNull Publisher<? extends MaybeSource<? extends T>> sources)
```
 Concatenates the Publisher sequence of Publishers into a single sequence by subscribing to each inner Publisher, one after the other, one at a time and delays any errors till the all inner and the outer Publishers terminate.
 
 Backpressure:
 
 concatDelayError fully supports backpressure.
 
 Scheduler:
 
 concatDelayError does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the common element base type
 
 Parameters:
 
 sources - the Publisher sequence of Publishers
 
 Returns:
 
 the new Publisher with the concatenating behavior
 - concatEager
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public static <T> @NonNull Flowable<T> concatEager(@NonNull @NonNull Iterable<? extends MaybeSource<? extends T>> sources)
```
 Concatenates a sequence of MaybeSources eagerly into a single stream of values.
 Eager concatenation means that once a subscriber subscribes, this operator subscribes to all of the source MaybeSources. The operator buffers the values emitted by these MaybeSources and then drains them in order, each one after the previous one completes.
 
 Backpressure:
 
 Backpressure is honored towards the downstream.
 
 Scheduler:
 
 This method does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the value type
 
 Parameters:
 
 sources - a sequence of MaybeSource that need to be eagerly concatenated
 
 Returns:
 
 the new Flowable instance with the specified concatenation behavior
 - concatEager
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public static <T> @NonNull Flowable<T> concatEager(@NonNull @NonNull Publisher<? extends MaybeSource<? extends T>> sources)
```
 Concatenates a Publisher sequence of MaybeSources eagerly into a single stream of values.
 Eager concatenation means that once a subscriber subscribes, this operator subscribes to all of the emitted source Publishers as they are observed. The operator buffers the values emitted by these Publishers and then drains them in order, each one after the previous one completes.
 
 Backpressure:
 
 Backpressure is honored towards the downstream and the outer Publisher is expected to support backpressure. Violating this assumption, the operator will signal MissingBackpressureException.
 
 Scheduler:
 
 This method does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the value type
 
 Parameters:
 
 sources - a sequence of Publishers that need to be eagerly concatenated
 
 Returns:
 
 the new Publisher instance with the specified concatenation behavior
 - create
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Maybe<T> create(@NonNull @NonNull MaybeOnSubscribe<T> onSubscribe)
```
 Provides an API (via a cold Maybe) that bridges the reactive world with the callback-style world.
 Example:
```
 Maybe.<Event>create(emitter -> {
 Callback listener = new Callback() {
 @Override
 public void onEvent(Event e) {
 if (e.isNothing()) {
 emitter.onComplete();
 } else {
 emitter.onSuccess(e);
 }
 }

 @Override
 public void onFailure(Exception e) {
 emitter.onError(e);
 }
 };

 AutoCloseable c = api.someMethod(listener);

 emitter.setCancellable(c::close);

 });
 
```
 Whenever a MaybeObserver subscribes to the returned Maybe, the provided MaybeOnSubscribe callback is invoked with a fresh instance of a MaybeEmitter that will interact only with that specific MaybeObserver. If this MaybeObserver disposes the flow (making MaybeEmitter.isDisposed() return true), other observers subscribed to the same returned Maybe are not affected.
 
 Scheduler:
 
 create does not operate by default on a particular Scheduler.
 Type Parameters:
 
 T - the value type
 
 Parameters:
 
 onSubscribe - the emitter that is called when a MaybeObserver subscribes to the returned Maybe
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 MaybeOnSubscribe, Cancellable
 - defer
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Maybe<T> defer(@NonNull @NonNull Supplier<? extends MaybeSource<? extends T>> maybeSupplier)
```
 Calls a Supplier for each individual MaybeObserver to return the actual MaybeSource source to be subscribed to.
 
 Scheduler:
 
 defer does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the value type
 
 Parameters:
 
 maybeSupplier - the Supplier that is called for each individual MaybeObserver and returns a MaybeSource instance to subscribe to
 
 Returns:
 
 the new Maybe instance
 - empty
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public static <T> @NonNull Maybe<T> empty()
```
 Returns a (singleton) Maybe instance that calls onComplete immediately.
 
 Scheduler:
 
 empty does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the value type
 
 Returns:
 
 the new Maybe instance
 - error
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Maybe<T> error(@NonNull @NonNull Throwable exception)
```
 Returns a Maybe that invokes a subscriber's onError method when the subscriber subscribes to it.
 
 Scheduler:
 
 error does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the type of the item (ostensibly) emitted by the Maybe
 
 Parameters:
 
 exception - the particular Throwable to pass to onError
 
 Returns:
 
 a Maybe that invokes the subscriber's onError method when the subscriber subscribes to it
 
 See Also:
 
 ReactiveX operators documentation: Throw
 - error
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Maybe<T> error(@NonNull @NonNull Supplier<? extends Throwable> supplier)
```
 Returns a Maybe that invokes a MaybeObserver's onError method when the MaybeObserver subscribes to it.
 
 Scheduler:
 
 error does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the type of the items (ostensibly) emitted by the Maybe
 
 Parameters:
 
 supplier - a Supplier factory to return a Throwable for each individual MaybeObserver
 
 Returns:
 
 a Maybe that invokes the MaybeObserver's onError method when the MaybeObserver subscribes to it
 
 See Also:
 
 ReactiveX operators documentation: Throw
 - fromAction
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Maybe<T> fromAction(@NonNull @NonNull Action run)
```
 Returns a Maybe instance that runs the given Action for each subscriber and emits either its exception or simply completes.
 
 Scheduler:
 
 fromAction does not operate by default on a particular Scheduler.
 
 Error handling:
 
 If the Action throws an exception, the respective Throwable is delivered to the downstream via MaybeObserver.onError(Throwable), except when the downstream has disposed this Maybe source. In this latter case, the Throwable is delivered to the global error handler via RxJavaPlugins.onError(Throwable) as an UndeliverableException.
 
 Type Parameters:
 
 T - the target type
 
 Parameters:
 
 run - the runnable to run for each subscriber
 
 Returns:
 
 the new Maybe instance
 
 Throws:
 
 NullPointerException - if run is null
 - fromCompletable
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Maybe<T> fromCompletable(@NonNull @NonNull CompletableSource completableSource)
```
 Wraps a CompletableSource into a Maybe.
 
 Scheduler:
 
 fromCompletable does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the target type
 
 Parameters:
 
 completableSource - the CompletableSource to convert from
 
 Returns:
 
 the new Maybe instance
 
 Throws:
 
 NullPointerException - if completable is null
 - fromSingle
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Maybe<T> fromSingle(@NonNull @NonNull SingleSource<T> singleSource)
```
 Wraps a SingleSource into a Maybe.
 
 Scheduler:
 
 fromSingle does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the target type
 
 Parameters:
 
 singleSource - the SingleSource to convert from
 
 Returns:
 
 the new Maybe instance
 
 Throws:
 
 NullPointerException - if single is null
 - fromCallable
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Maybe<T> fromCallable(@NonNull @NonNull Callable<? extends T> callable)
```
 Returns a Maybe that invokes the given Callable for each individual MaybeObserver that subscribes and emits the resulting non-null item via onSuccess while considering a null result from the Callable as indication for valueless completion via onComplete.
 This operator allows you to defer the execution of the given Callable until a MaybeObserver subscribes to the returned Maybe. In other terms, this source operator evaluates the given Callable "lazily".
 Note that the null handling of this operator differs from the similar source operators in the other base reactive classes. Those operators signal a NullPointerException if the value returned by their Callable is null while this fromCallable considers it to indicate the returned Maybe is empty.
 
 Scheduler:
 
 fromCallable does not operate by default on a particular Scheduler.
 
 Error handling:
 
 Any non-fatal exception thrown by Callable.call() will be forwarded to onError, except if the MaybeObserver disposed the subscription in the meantime. In this latter case, the exception is forwarded to the global error handler via RxJavaPlugins.onError(Throwable) wrapped into a UndeliverableException. Fatal exceptions are rethrown and usually will end up in the executing thread's Thread.UncaughtExceptionHandler.uncaughtException(Thread, Throwable) handler.
 
 Type Parameters:
 
 T - the type of the item emitted by the Maybe.
 
 Parameters:
 
 callable - a Callable instance whose execution should be deferred and performed for each individual MaybeObserver that subscribes to the returned Maybe.
 
 Returns:
 
 a new Maybe instance
 
 See Also:
 
 defer(Supplier), fromSupplier(Supplier)
 - fromFuture
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Maybe<T> fromFuture(@NonNull @NonNull Future<? extends T> future)
```
 Converts a Future into a Maybe, treating a null result as an indication of emptiness.
 
 You can convert any object that supports the Future interface into a Maybe that emits the return value of the Future.get() method of that object, by passing the object into the from method.
 Important note: This Maybe is blocking; you cannot dispose it.
 Unlike 1.x, disposing the Maybe won't cancel the future. If necessary, one can use composition to achieve the cancellation effect: futureMaybe.doOnDispose(() -> future.cancel(true));.
 
 Scheduler:
 
 fromFuture does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the type of object that the Future returns, and also the type of item to be emitted by the resulting Maybe
 
 Parameters:
 
 future - the source Future
 
 Returns:
 
 a Maybe that emits the item from the source Future
 
 See Also:
 
 ReactiveX operators documentation: From
 - fromFuture
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Maybe<T> fromFuture(@NonNull @NonNull Future<? extends T> future,
 long timeout,
 @NonNull @NonNull TimeUnit unit)
```
 Converts a Future into a Maybe, with a timeout on the Future.
 
 You can convert any object that supports the Future interface into a Maybe that emits the return value of the Future.get() method of that object, by passing the object into the fromFuture method.
 Unlike 1.x, disposing the Maybe won't cancel the future. If necessary, one can use composition to achieve the cancellation effect: futureMaybe.doOnCancel(() -> future.cancel(true));.
 Important note: This Maybe is blocking on the thread it gets subscribed on; you cannot dispose it.
 
 Scheduler:
 
 fromFuture does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the type of object that the Future returns, and also the type of item to be emitted by the resulting Maybe
 
 Parameters:
 
 future - the source Future
 
 timeout - the maximum time to wait before calling get
 
 unit - the TimeUnit of the timeout argument
 
 Returns:
 
 a Maybe that emits the item from the source Future
 
 See Also:
 
 ReactiveX operators documentation: From
 - fromRunnable
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Maybe<T> fromRunnable(@NonNull @NonNull Runnable run)
```
 Returns a Maybe instance that runs the given Action for each subscriber and emits either its exception or simply completes.
 
 Scheduler:
 
 fromRunnable does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the target type
 
 Parameters:
 
 run - the runnable to run for each subscriber
 
 Returns:
 
 the new Maybe instance
 
 Throws:
 
 NullPointerException - if run is null
 - fromSupplier
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Maybe<T> fromSupplier(@NonNull @NonNull Supplier<? extends T> supplier)
```
 Returns a Maybe that invokes the given Supplier for each individual MaybeObserver that subscribes and emits the resulting non-null item via onSuccess while considering a null result from the Supplier as indication for valueless completion via onComplete.
 This operator allows you to defer the execution of the given Supplier until a MaybeObserver subscribes to the returned Maybe. In other terms, this source operator evaluates the given Supplier "lazily".
 
 Note that the null handling of this operator differs from the similar source operators in the other base reactive classes. Those operators signal a NullPointerException if the value returned by their Supplier is null while this fromSupplier considers it to indicate the returned Maybe is empty.
 
 Scheduler:
 
 fromSupplier does not operate by default on a particular Scheduler.
 
 Error handling:
 
 Any non-fatal exception thrown by Supplier.get() will be forwarded to onError, except if the MaybeObserver disposed the subscription in the meantime. In this latter case, the exception is forwarded to the global error handler via RxJavaPlugins.onError(Throwable) wrapped into a UndeliverableException. Fatal exceptions are rethrown and usually will end up in the executing thread's Thread.UncaughtExceptionHandler.uncaughtException(Thread, Throwable) handler.
 
 Type Parameters:
 
 T - the type of the item emitted by the Maybe.
 
 Parameters:
 
 supplier - a Supplier instance whose execution should be deferred and performed for each individual MaybeObserver that subscribes to the returned Maybe.
 
 Returns:
 
 a new Maybe instance
 
 Since:
 
 3.0.0
 
 See Also:
 
 defer(Supplier), fromCallable(Callable)
 - just
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Maybe<T> just(T item)
```
 Returns a Maybe that emits a specified item.
 
 To convert any object into a Maybe that emits that object, pass that object into the just method.
 
 Scheduler:
 
 just does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the type of that item
 
 Parameters:
 
 item - the item to emit
 
 Returns:
 
 a Maybe that emits item
 
 See Also:
 
 ReactiveX operators documentation: Just
 - merge
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public static <T> @NonNull Flowable<T> merge(@NonNull @NonNull Iterable<? extends MaybeSource<? extends T>> sources)
```
 Merges an Iterable sequence of MaybeSource instances into a single Flowable sequence, running all MaybeSources at once.
 
 Backpressure:
 
 The operator honors backpressure from downstream.
 
 Scheduler:
 
 merge does not operate by default on a particular Scheduler.
 
 Error handling:
 
 If any of the source MaybeSources signal a Throwable via onError, the resulting Flowable terminates with that Throwable and all other source MaybeSources are disposed. If more than one MaybeSource signals an error, the resulting Flowable may terminate with the first one's error or, depending on the concurrency of the sources, may terminate with a CompositeException containing two or more of the various error signals. Throwables that didn't make into the composite will be sent (individually) to the global error handler via RxJavaPlugins.onError(Throwable) method as UndeliverableException errors. Similarly, Throwables signaled by source(s) after the returned Flowable has been cancelled or terminated with a (composite) error will be sent to the same global error handler. Use mergeDelayError(Iterable) to merge sources and terminate only when all source MaybeSources have completed or failed with an error.
 
 Type Parameters:
 
 T - the common and resulting value type
 
 Parameters:
 
 sources - the Iterable sequence of MaybeSource sources
 
 Returns:
 
 the new Flowable instance
 
 See Also:
 
 mergeDelayError(Iterable)
 - merge
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public static <T> @NonNull Flowable<T> merge(@NonNull @NonNull Publisher<? extends MaybeSource<? extends T>> sources)
```
 Merges a Flowable sequence of MaybeSource instances into a single Flowable sequence, running all MaybeSources at once.
 
 Backpressure:
 
 The operator honors backpressure from downstream.
 
 Scheduler:
 
 merge does not operate by default on a particular Scheduler.
 
 Error handling:
 
 If any of the source MaybeSources signal a Throwable via onError, the resulting Flowable terminates with that Throwable and all other source MaybeSources are disposed. If more than one MaybeSource signals an error, the resulting Flowable may terminate with the first one's error or, depending on the concurrency of the sources, may terminate with a CompositeException containing two or more of the various error signals. Throwables that didn't make into the composite will be sent (individually) to the global error handler via RxJavaPlugins.onError(Throwable) method as UndeliverableException errors. Similarly, Throwables signaled by source(s) after the returned Flowable has been cancelled or terminated with a (composite) error will be sent to the same global error handler. Use mergeDelayError(Publisher) to merge sources and terminate only when all source MaybeSources have completed or failed with an error.
 
 Type Parameters:
 
 T - the common and resulting value type
 
 Parameters:
 
 sources - the Flowable sequence of MaybeSource sources
 
 Returns:
 
 the new Flowable instance
 
 See Also:
 
 mergeDelayError(Publisher)
 - merge
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Flowable<T> merge(@NonNull @NonNull Publisher<? extends MaybeSource<? extends T>> sources,
 int maxConcurrency)
```
 Merges a Flowable sequence of MaybeSource instances into a single Flowable sequence, running at most maxConcurrency MaybeSources at once.
 
 Backpressure:
 
 The operator honors backpressure from downstream.
 
 Scheduler:
 
 merge does not operate by default on a particular Scheduler.
 
 Error handling:
 
 If any of the source MaybeSources signal a Throwable via onError, the resulting Flowable terminates with that Throwable and all other source MaybeSources are disposed. If more than one MaybeSource signals an error, the resulting Flowable may terminate with the first one's error or, depending on the concurrency of the sources, may terminate with a CompositeException containing two or more of the various error signals. Throwables that didn't make into the composite will be sent (individually) to the global error handler via RxJavaPlugins.onError(Throwable) method as UndeliverableException errors. Similarly, Throwables signaled by source(s) after the returned Flowable has been cancelled or terminated with a (composite) error will be sent to the same global error handler. Use mergeDelayError(Publisher, int) to merge sources and terminate only when all source MaybeSources have completed or failed with an error.
 
 Type Parameters:
 
 T - the common and resulting value type
 
 Parameters:
 
 sources - the Flowable sequence of MaybeSource sources
 
 maxConcurrency - the maximum number of concurrently running MaybeSources
 
 Returns:
 
 the new Flowable instance
 
 See Also:
 
 mergeDelayError(Publisher, int)
 - merge
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Maybe<T> merge(@NonNull @NonNull MaybeSource<? extends MaybeSource<? extends T>> source)
```
 Flattens a MaybeSource that emits a MaybeSource into a single MaybeSource that emits the item emitted by the nested MaybeSource, without any transformation.
 
 Scheduler:
 
 merge does not operate by default on a particular Scheduler.
 
 Error handling:
 
 The resulting Maybe emits the outer source's or the inner MaybeSource's Throwable as is. Unlike the other merge() operators, this operator won't and can't produce a CompositeException because there is only one possibility for the outer or the inner MaybeSource to emit an onError signal. Therefore, there is no need for a mergeDelayError(MaybeSource<MaybeSource<T>>) operator.
 
 Type Parameters:
 
 T - the value type of the sources and the output
 
 Parameters:
 
 source - a MaybeSource that emits a MaybeSource
 
 Returns:
 
 a Maybe that emits the item that is the result of flattening the MaybeSource emitted by source
 
 See Also:
 
 ReactiveX operators documentation: Merge
 - merge
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Flowable<T> merge(@NonNull @NonNull MaybeSource<? extends T> source1,
 @NonNull @NonNull MaybeSource<? extends T> source2)
```
 Flattens two MaybeSources into a single Flowable, without any transformation.
 
 You can combine items emitted by multiple MaybeSources so that they appear as a single Flowable, by using the merge method.
 
 Backpressure:
 
 The operator honors backpressure from downstream.
 
 Scheduler:
 
 merge does not operate by default on a particular Scheduler.
 
 Error handling:
 
 If any of the source MaybeSources signal a Throwable via onError, the resulting Flowable terminates with that Throwable and all other source MaybeSources are disposed. If more than one MaybeSource signals an error, the resulting Flowable may terminate with the first one's error or, depending on the concurrency of the sources, may terminate with a CompositeException containing two or more of the various error signals. Throwables that didn't make into the composite will be sent (individually) to the global error handler via RxJavaPlugins.onError(Throwable) method as UndeliverableException errors. Similarly, Throwables signaled by source(s) after the returned Flowable has been cancelled or terminated with a (composite) error will be sent to the same global error handler. Use mergeDelayError(MaybeSource, MaybeSource) to merge sources and terminate only when all source MaybeSources have completed or failed with an error.
 
 Type Parameters:
 
 T - the common value type
 
 Parameters:
 
 source1 - a MaybeSource to be merged
 
 source2 - a MaybeSource to be merged
 
 Returns:
 
 a Flowable that emits all of the items emitted by the source MaybeSources
 
 See Also:
 
 ReactiveX operators documentation: Merge, mergeDelayError(MaybeSource, MaybeSource)
 - merge
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Flowable<T> merge(@NonNull @NonNull MaybeSource<? extends T> source1,
 @NonNull @NonNull MaybeSource<? extends T> source2,
 @NonNull @NonNull MaybeSource<? extends T> source3)
```
 Flattens three MaybeSources into a single Flowable, without any transformation.
 
 You can combine items emitted by multiple MaybeSources so that they appear as a single Flowable, by using the merge method.
 
 Backpressure:
 
 The operator honors backpressure from downstream.
 
 Scheduler:
 
 merge does not operate by default on a particular Scheduler.
 
 Error handling:
 
 If any of the source MaybeSources signal a Throwable via onError, the resulting Flowable terminates with that Throwable and all other source MaybeSources are disposed. If more than one MaybeSource signals an error, the resulting Flowable may terminate with the first one's error or, depending on the concurrency of the sources, may terminate with a CompositeException containing two or more of the various error signals. Throwables that didn't make into the composite will be sent (individually) to the global error handler via RxJavaPlugins.onError(Throwable) method as UndeliverableException errors. Similarly, Throwables signaled by source(s) after the returned Flowable has been cancelled or terminated with a (composite) error will be sent to the same global error handler. Use mergeDelayError(MaybeSource, MaybeSource, MaybeSource) to merge sources and terminate only when all source MaybeSources have completed or failed with an error.
 
 Type Parameters:
 
 T - the common value type
 
 Parameters:
 
 source1 - a MaybeSource to be merged
 
 source2 - a MaybeSource to be merged
 
 source3 - a MaybeSource to be merged
 
 Returns:
 
 a Flowable that emits all of the items emitted by the source MaybeSources
 
 See Also:
 
 ReactiveX operators documentation: Merge, mergeDelayError(MaybeSource, MaybeSource, MaybeSource)
 - merge
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Flowable<T> merge(@NonNull @NonNull MaybeSource<? extends T> source1,
 @NonNull @NonNull MaybeSource<? extends T> source2,
 @NonNull @NonNull MaybeSource<? extends T> source3,
 @NonNull @NonNull MaybeSource<? extends T> source4)
```
 Flattens four MaybeSources into a single Flowable, without any transformation.
 
 You can combine items emitted by multiple MaybeSources so that they appear as a single Flowable, by using the merge method.
 
 Backpressure:
 
 The operator honors backpressure from downstream.
 
 Scheduler:
 
 merge does not operate by default on a particular Scheduler.
 
 Error handling:
 
 If any of the source MaybeSources signal a Throwable via onError, the resulting Flowable terminates with that Throwable and all other source MaybeSources are disposed. If more than one MaybeSource signals an error, the resulting Flowable may terminate with the first one's error or, depending on the concurrency of the sources, may terminate with a CompositeException containing two or more of the various error signals. Throwables that didn't make into the composite will be sent (individually) to the global error handler via RxJavaPlugins.onError(Throwable) method as UndeliverableException errors. Similarly, Throwables signaled by source(s) after the returned Flowable has been cancelled or terminated with a (composite) error will be sent to the same global error handler. Use mergeDelayError(MaybeSource, MaybeSource, MaybeSource, MaybeSource) to merge sources and terminate only when all source MaybeSources have completed or failed with an error.
 
 Type Parameters:
 
 T - the common value type
 
 Parameters:
 
 source1 - a MaybeSource to be merged
 
 source2 - a MaybeSource to be merged
 
 source3 - a MaybeSource to be merged
 
 source4 - a MaybeSource to be merged
 
 Returns:
 
 a Flowable that emits all of the items emitted by the source MaybeSources
 
 See Also:
 
 ReactiveX operators documentation: Merge, mergeDelayError(MaybeSource, MaybeSource, MaybeSource, MaybeSource)
 - mergeArray
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
 @SafeVarargs
public static <T> @NonNull Flowable<T> mergeArray(MaybeSource<? extends T>... sources)
```
 Merges an array sequence of MaybeSource instances into a single Flowable sequence, running all MaybeSources at once.
 
 Backpressure:
 
 The operator honors backpressure from downstream.
 
 Scheduler:
 
 mergeArray does not operate by default on a particular Scheduler.
 
 Error handling:
 
 If any of the source MaybeSources signal a Throwable via onError, the resulting Flowable terminates with that Throwable and all other source MaybeSources are disposed. If more than one MaybeSource signals an error, the resulting Flowable may terminate with the first one's error or, depending on the concurrency of the sources, may terminate with a CompositeException containing two or more of the various error signals. Throwables that didn't make into the composite will be sent (individually) to the global error handler via RxJavaPlugins.onError(Throwable) method as UndeliverableException errors. Similarly, Throwables signaled by source(s) after the returned Flowable has been cancelled or terminated with a (composite) error will be sent to the same global error handler. Use mergeArrayDelayError(MaybeSource...) to merge sources and terminate only when all source MaybeSources have completed or failed with an error.
 
 Type Parameters:
 
 T - the common and resulting value type
 
 Parameters:
 
 sources - the array sequence of MaybeSource sources
 
 Returns:
 
 the new Flowable instance
 
 See Also:
 
 mergeArrayDelayError(MaybeSource...)
 - mergeArrayDelayError
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @SchedulerSupport(value="none")
 @SafeVarargs
 @NonNull
public static <T> @NonNull Flowable<T> mergeArrayDelayError(@NonNull MaybeSource<? extends T>... sources)
```
 Flattens an array of MaybeSources into one Flowable, in a way that allows a Subscriber to receive all successfully emitted items from each of the source MaybeSources without being interrupted by an error notification from one of them.
 This behaves like merge(Publisher) except that if any of the merged MaybeSources notify of an error via onError, mergeDelayError will refrain from propagating that error notification until all of the merged MaybeSources have finished emitting items.
 
 Even if multiple merged MaybeSources send onError notifications, mergeDelayError will only invoke the onError method of its Subscribers once.
 
 Backpressure:
 
 The operator honors backpressure from downstream.
 
 Scheduler:
 
 mergeArrayDelayError does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the common element base type
 
 Parameters:
 
 sources - the Iterable of MaybeSources
 
 Returns:
 
 a Flowable that emits items that are the result of flattening the items emitted by the MaybeSources in the Iterable
 
 See Also:
 
 ReactiveX operators documentation: Merge
 - mergeDelayError
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public static <T> @NonNull Flowable<T> mergeDelayError(@NonNull @NonNull Iterable<? extends MaybeSource<? extends T>> sources)
```
 Flattens an Iterable of MaybeSources into one Flowable, in a way that allows a Subscriber to receive all successfully emitted items from each of the source MaybeSources without being interrupted by an error notification from one of them.
 This behaves like merge(Publisher) except that if any of the merged MaybeSources notify of an error via onError, mergeDelayError will refrain from propagating that error notification until all of the merged MaybeSources have finished emitting items.
 
 Even if multiple merged MaybeSources send onError notifications, mergeDelayError will only invoke the onError method of its Subscribers once.
 
 Backpressure:
 
 The operator honors backpressure from downstream.
 
 Scheduler:
 
 mergeDelayError does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the common element base type
 
 Parameters:
 
 sources - the Iterable of MaybeSources
 
 Returns:
 
 a Flowable that emits items that are the result of flattening the items emitted by the MaybeSources in the Iterable
 
 See Also:
 
 ReactiveX operators documentation: Merge
 - mergeDelayError
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public static <T> @NonNull Flowable<T> mergeDelayError(@NonNull @NonNull Publisher<? extends MaybeSource<? extends T>> sources)
```
 Flattens a Publisher that emits MaybeSources into one Publisher, in a way that allows a Subscriber to receive all successfully emitted items from all of the source MaybeSources without being interrupted by an error notification from one of them or even the main Publisher.
 This behaves like merge(Publisher) except that if any of the merged MaybeSources notify of an error via onError, mergeDelayError will refrain from propagating that error notification until all of the merged MaybeSources and the main Publisher have finished emitting items.
 
 Even if multiple merged Publishers send onError notifications, mergeDelayError will only invoke the onError method of its Subscribers once.
 
 Backpressure:
 
 The operator honors backpressure from downstream. The outer Publisher is consumed in unbounded mode (i.e., no backpressure is applied to it).
 
 Scheduler:
 
 mergeDelayError does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the common element base type
 
 Parameters:
 
 sources - a Publisher that emits MaybeSources
 
 Returns:
 
 a Flowable that emits all of the items emitted by the Publishers emitted by the source Publisher
 
 See Also:
 
 ReactiveX operators documentation: Merge
 - mergeDelayError
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Flowable<T> mergeDelayError(@NonNull @NonNull Publisher<? extends MaybeSource<? extends T>> sources,
 int maxConcurrency)
```
 Flattens a Publisher that emits MaybeSources into one Publisher, in a way that allows a Subscriber to receive all successfully emitted items from all of the source MaybeSources without being interrupted by an error notification from one of them or even the main Publisher as well as limiting the total number of active MaybeSources.
 This behaves like merge(Publisher, int) except that if any of the merged MaybeSources notify of an error via onError, mergeDelayError will refrain from propagating that error notification until all of the merged MaybeSources and the main Publisher have finished emitting items.
 
 Even if multiple merged Publishers send onError notifications, mergeDelayError will only invoke the onError method of its Subscribers once.
 
 Backpressure:
 
 The operator honors backpressure from downstream. The outer Publisher is consumed in unbounded mode (i.e., no backpressure is applied to it).
 
 Scheduler:
 
 mergeDelayError does not operate by default on a particular Scheduler.
 
 History: 2.1.9 - experimental
 
 Type Parameters:
 
 T - the common element base type
 
 Parameters:
 
 sources - a Publisher that emits MaybeSources
 
 maxConcurrency - the maximum number of active inner MaybeSources to be merged at a time
 
 Returns:
 
 a Flowable that emits all of the items emitted by the Publishers emitted by the source Publisher
 
 Since:
 
 2.2
 
 See Also:
 
 ReactiveX operators documentation: Merge
 - mergeDelayError
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Flowable<T> mergeDelayError(@NonNull @NonNull MaybeSource<? extends T> source1,
 @NonNull @NonNull MaybeSource<? extends T> source2)
```
 Flattens two MaybeSources into one Flowable, in a way that allows a Subscriber to receive all successfully emitted items from each of the source MaybeSources without being interrupted by an error notification from one of them.
 This behaves like merge(MaybeSource, MaybeSource) except that if any of the merged MaybeSources notify of an error via onError, mergeDelayError will refrain from propagating that error notification until all of the merged MaybeSources have finished emitting items.
 
 Even if both merged MaybeSources send onError notifications, mergeDelayError will only invoke the onError method of its Subscribers once.
 
 Backpressure:
 
 The operator honors backpressure from downstream.
 
 Scheduler:
 
 mergeDelayError does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the common element base type
 
 Parameters:
 
 source1 - a MaybeSource to be merged
 
 source2 - a MaybeSource to be merged
 
 Returns:
 
 a Flowable that emits all of the items that are emitted by the two source MaybeSources
 
 See Also:
 
 ReactiveX operators documentation: Merge
 - mergeDelayError
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Flowable<T> mergeDelayError(@NonNull @NonNull MaybeSource<? extends T> source1,
 @NonNull @NonNull MaybeSource<? extends T> source2,
 @NonNull @NonNull MaybeSource<? extends T> source3)
```
 Flattens three MaybeSource into one Flowable, in a way that allows a Subscriber to receive all successfully emitted items from all of the source MaybeSources without being interrupted by an error notification from one of them.
 This behaves like merge(MaybeSource, MaybeSource, MaybeSource) except that if any of the merged MaybeSources notify of an error via onError, mergeDelayError will refrain from propagating that error notification until all of the merged MaybeSources have finished emitting items.
 
 Even if multiple merged MaybeSources send onError notifications, mergeDelayError will only invoke the onError method of its Subscribers once.
 
 Backpressure:
 
 The operator honors backpressure from downstream.
 
 Scheduler:
 
 mergeDelayError does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the common element base type
 
 Parameters:
 
 source1 - a MaybeSource to be merged
 
 source2 - a MaybeSource to be merged
 
 source3 - a MaybeSource to be merged
 
 Returns:
 
 a Flowable that emits all of the items that are emitted by the source MaybeSources
 
 See Also:
 
 ReactiveX operators documentation: Merge
 - mergeDelayError
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Flowable<T> mergeDelayError(@NonNull @NonNull MaybeSource<? extends T> source1,
 @NonNull @NonNull MaybeSource<? extends T> source2,
 @NonNull @NonNull MaybeSource<? extends T> source3,
 @NonNull @NonNull MaybeSource<? extends T> source4)
```
 Flattens four MaybeSources into one Flowable, in a way that allows a Subscriber to receive all successfully emitted items from all of the source MaybeSources without being interrupted by an error notification from one of them.
 This behaves like merge(MaybeSource, MaybeSource, MaybeSource, MaybeSource) except that if any of the merged MaybeSources notify of an error via onError, mergeDelayError will refrain from propagating that error notification until all of the merged MaybeSources have finished emitting items.
 
 Even if multiple merged MaybeSources send onError notifications, mergeDelayError will only invoke the onError method of its Subscribers once.
 
 Backpressure:
 
 The operator honors backpressure from downstream.
 
 Scheduler:
 
 mergeDelayError does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the common element base type
 
 Parameters:
 
 source1 - a MaybeSource to be merged
 
 source2 - a MaybeSource to be merged
 
 source3 - a MaybeSource to be merged
 
 source4 - a MaybeSource to be merged
 
 Returns:
 
 a Flowable that emits all of the items that are emitted by the source MaybeSources
 
 See Also:
 
 ReactiveX operators documentation: Merge
 - never
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public static <T> @NonNull Maybe<T> never()
```
 Returns a Maybe that never sends any items or notifications to a MaybeObserver.
 
 This Maybe is useful primarily for testing purposes.
 
 Scheduler:
 
 never does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the type of items (not) emitted by the Maybe
 
 Returns:
 
 a Maybe that never emits any items or sends any notifications to a MaybeObserver
 
 See Also:
 
 ReactiveX operators documentation: Never
 - sequenceEqual
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public static <T> @NonNull Single<Boolean> sequenceEqual(@NonNull @NonNull MaybeSource<? extends T> source1,
 @NonNull @NonNull MaybeSource<? extends T> source2)
```
 Returns a Single that emits a Boolean value that indicates whether two MaybeSource sequences are the same by comparing the items emitted by each MaybeSource pairwise.
 
 Scheduler:
 
 sequenceEqual does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the type of items emitted by each MaybeSource
 
 Parameters:
 
 source1 - the first MaybeSource to compare
 
 source2 - the second MaybeSource to compare
 
 Returns:
 
 a Single that emits a Boolean value that indicates whether the two sequences are the same
 
 See Also:
 
 ReactiveX operators documentation: SequenceEqual
 - sequenceEqual
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Single<Boolean> sequenceEqual(@NonNull @NonNull MaybeSource<? extends T> source1,
 @NonNull @NonNull MaybeSource<? extends T> source2,
 @NonNull @NonNull BiPredicate<? super T,? super T> isEqual)
```
 Returns a Single that emits a Boolean value that indicates whether two MaybeSources are the same by comparing the items emitted by each MaybeSource pairwise based on the results of a specified equality function.
 
 Scheduler:
 
 sequenceEqual does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the type of items emitted by each MaybeSource
 
 Parameters:
 
 source1 - the first MaybeSource to compare
 
 source2 - the second MaybeSource to compare
 
 isEqual - a function used to compare items emitted by each MaybeSource
 
 Returns:
 
 a Single that emits a Boolean value that indicates whether the two MaybeSource sequences are the same according to the specified function
 
 See Also:
 
 ReactiveX operators documentation: SequenceEqual
 - timer
```
@CheckReturnValue
 @SchedulerSupport(value="io.reactivex:computation")
 @NonNull
public static @NonNull Maybe<Long> timer(long delay,
 @NonNull @NonNull TimeUnit unit)
```
 Returns a Maybe that emits 0L after a specified delay.
 
 Scheduler:
 
 timer operates by default on the computation Scheduler.
 
 Parameters:
 
 delay - the initial delay before emitting a single 0L
 
 unit - time units to use for delay
 
 Returns:
 
 a Maybe that emits 0L after a specified delay
 
 See Also:
 
 ReactiveX operators documentation: Timer
 - timer
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="custom")
public static @NonNull Maybe<Long> timer(long delay,
 @NonNull @NonNull TimeUnit unit,
 @NonNull @NonNull Scheduler scheduler)
```
 Returns a Maybe that emits 0L after a specified delay on a specified Scheduler.
 
 Scheduler:
 
 You specify which Scheduler this operator will use.
 
 Parameters:
 
 delay - the initial delay before emitting a single 0L
 
 unit - time units to use for delay
 
 scheduler - the Scheduler to use for scheduling the item
 
 Returns:
 
 a Maybe that emits 0L after a specified delay, on a specified Scheduler
 
 See Also:
 
 ReactiveX operators documentation: Timer
 - unsafeCreate
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Maybe<T> unsafeCreate(@NonNull @NonNull MaybeSource<T> onSubscribe)
```
 Advanced use only: creates a Maybe instance without any safeguards by using a callback that is called with a MaybeObserver.
 
 Scheduler:
 
 unsafeCreate does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the value type
 
 Parameters:
 
 onSubscribe - the function that is called with the subscribing MaybeObserver
 
 Returns:
 
 the new Maybe instance
 - using
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public static <T,D> @NonNull Maybe<T> using(@NonNull @NonNull Supplier<? extends D> resourceSupplier,
 @NonNull @NonNull Function<? super D,? extends MaybeSource<? extends T>> sourceSupplier,
 @NonNull @NonNull Consumer<? super D> resourceDisposer)
```
 Constructs a Maybe that creates a dependent resource object which is disposed of when the upstream terminates or the downstream calls dispose().
 
 Scheduler:
 
 using does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the element type of the generated MaybeSource
 
 D - the type of the resource associated with the output sequence
 
 Parameters:
 
 resourceSupplier - the factory function to create a resource object that depends on the Maybe
 
 sourceSupplier - the factory function to create a MaybeSource
 
 resourceDisposer - the function that will dispose of the resource
 
 Returns:
 
 the Maybe whose lifetime controls the lifetime of the dependent resource object
 
 See Also:
 
 ReactiveX operators documentation: Using
 - using
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T,D> @NonNull Maybe<T> using(@NonNull @NonNull Supplier<? extends D> resourceSupplier,
 @NonNull @NonNull Function<? super D,? extends MaybeSource<? extends T>> sourceSupplier,
 @NonNull @NonNull Consumer<? super D> resourceDisposer,
 boolean eager)
```
 Constructs a Maybe that creates a dependent resource object which is disposed of just before termination if you have set disposeEagerly to true and a downstream dispose() does not occur before termination. Otherwise resource disposal will occur on call to dispose(). Eager disposal is particularly appropriate for a synchronous Maybe that reuses resources. disposeAction will only be called once per subscription.
 
 Scheduler:
 
 using does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the element type of the generated MaybeSource
 
 D - the type of the resource associated with the output sequence
 
 Parameters:
 
 resourceSupplier - the factory function to create a resource object that depends on the Maybe
 
 sourceSupplier - the factory function to create a MaybeSource
 
 resourceDisposer - the function that will dispose of the resource
 
 eager - If true then resource disposal will happen either on a dispose() call before the upstream is disposed or just before the emission of a terminal event (onSuccess, onComplete or onError). If false the resource disposal will happen either on a dispose() call after the upstream is disposed or just after the emission of a terminal event (onSuccess, onComplete or onError).
 
 Returns:
 
 the Maybe whose lifetime controls the lifetime of the dependent resource object
 
 See Also:
 
 ReactiveX operators documentation: Using
 - wrap
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T> @NonNull Maybe<T> wrap(@NonNull @NonNull MaybeSource<T> source)
```
 Wraps a MaybeSource instance into a new Maybe instance if not already a Maybe instance.
 
 Scheduler:
 
 wrap does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the value type
 
 Parameters:
 
 source - the source to wrap
 
 Returns:
 
 the Maybe wrapper or the source cast to Maybe (if possible)
 - zip
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T,R> @NonNull Maybe<R> zip(@NonNull @NonNull Iterable<? extends MaybeSource<? extends T>> sources,
 @NonNull @NonNull Function<? super Object[],? extends R> zipper)
```
 Returns a Maybe that emits the results of a specified combiner function applied to combinations of items emitted, in sequence, by an Iterable of other MaybeSources.
 
 Note on method signature: since Java doesn't allow creating a generic array with new T[], the implementation of this operator has to create an Object[] instead. Unfortunately, a Function<Integer[], R> passed to the method would trigger a ClassCastException.
 This operator terminates eagerly if any of the source MaybeSources signal an onError or onComplete. This also means it is possible some sources may not get subscribed to at all.
 
 Scheduler:
 
 zip does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the common value type
 
 R - the zipped result type
 
 Parameters:
 
 sources - an Iterable of source MaybeSources
 
 zipper - a function that, when applied to an item emitted by each of the source MaybeSources, results in an item that will be emitted by the resulting Maybe
 
 Returns:
 
 a Maybe that emits the zipped results
 
 See Also:
 
 ReactiveX operators documentation: Zip
 - zip
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T1,T2,R> @NonNull Maybe<R> zip(@NonNull @NonNull MaybeSource<? extends T1> source1,
 @NonNull @NonNull MaybeSource<? extends T2> source2,
 @NonNull @NonNull BiFunction<? super T1,? super T2,? extends R> zipper)
```
 Returns a Maybe that emits the results of a specified combiner function applied to combinations of two items emitted, in sequence, by two other MaybeSources.
 
 This operator terminates eagerly if any of the source MaybeSources signal an onError or onComplete. This also means it is possible some sources may not get subscribed to at all.
 
 Scheduler:
 
 zip does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T1 - the value type of the first source
 
 T2 - the value type of the second source
 
 R - the zipped result type
 
 Parameters:
 
 source1 - the first source MaybeSource
 
 source2 - a second source MaybeSource
 
 zipper - a function that, when applied to an item emitted by each of the source MaybeSources, results in an item that will be emitted by the resulting Maybe
 
 Returns:
 
 a Maybe that emits the zipped results
 
 See Also:
 
 ReactiveX operators documentation: Zip
 - zip
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T1,T2,T3,R> @NonNull Maybe<R> zip(@NonNull @NonNull MaybeSource<? extends T1> source1,
 @NonNull @NonNull MaybeSource<? extends T2> source2,
 @NonNull @NonNull MaybeSource<? extends T3> source3,
 @NonNull @NonNull Function3<? super T1,? super T2,? super T3,? extends R> zipper)
```
 Returns a Maybe that emits the results of a specified combiner function applied to combinations of three items emitted, in sequence, by three other MaybeSources.
 
 This operator terminates eagerly if any of the source MaybeSources signal an onError or onComplete. This also means it is possible some sources may not get subscribed to at all.
 
 Scheduler:
 
 zip does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T1 - the value type of the first source
 
 T2 - the value type of the second source
 
 T3 - the value type of the third source
 
 R - the zipped result type
 
 Parameters:
 
 source1 - the first source MaybeSource
 
 source2 - a second source MaybeSource
 
 source3 - a third source MaybeSource
 
 zipper - a function that, when applied to an item emitted by each of the source MaybeSources, results in an item that will be emitted by the resulting Maybe
 
 Returns:
 
 a Maybe that emits the zipped results
 
 See Also:
 
 ReactiveX operators documentation: Zip
 - zip
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T1,T2,T3,T4,R> @NonNull Maybe<R> zip(@NonNull @NonNull MaybeSource<? extends T1> source1,
 @NonNull @NonNull MaybeSource<? extends T2> source2,
 @NonNull @NonNull MaybeSource<? extends T3> source3,
 @NonNull @NonNull MaybeSource<? extends T4> source4,
 @NonNull @NonNull Function4<? super T1,? super T2,? super T3,? super T4,? extends R> zipper)
```
 Returns a Maybe that emits the results of a specified combiner function applied to combinations of four items emitted, in sequence, by four other MaybeSources.
 
 This operator terminates eagerly if any of the source MaybeSources signal an onError or onComplete. This also means it is possible some sources may not get subscribed to at all.
 
 Scheduler:
 
 zip does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T1 - the value type of the first source
 
 T2 - the value type of the second source
 
 T3 - the value type of the third source
 
 T4 - the value type of the fourth source
 
 R - the zipped result type
 
 Parameters:
 
 source1 - the first source MaybeSource
 
 source2 - a second source MaybeSource
 
 source3 - a third source MaybeSource
 
 source4 - a fourth source MaybeSource
 
 zipper - a function that, when applied to an item emitted by each of the source MaybeSources, results in an item that will be emitted by the resulting Maybe
 
 Returns:
 
 a Maybe that emits the zipped results
 
 See Also:
 
 ReactiveX operators documentation: Zip
 - zip
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T1,T2,T3,T4,T5,R> @NonNull Maybe<R> zip(@NonNull @NonNull MaybeSource<? extends T1> source1,
 @NonNull @NonNull MaybeSource<? extends T2> source2,
 @NonNull @NonNull MaybeSource<? extends T3> source3,
 @NonNull @NonNull MaybeSource<? extends T4> source4,
 @NonNull @NonNull MaybeSource<? extends T5> source5,
 @NonNull @NonNull Function5<? super T1,? super T2,? super T3,? super T4,? super T5,? extends R> zipper)
```
 Returns a Maybe that emits the results of a specified combiner function applied to combinations of five items emitted, in sequence, by five other MaybeSources.
 
 This operator terminates eagerly if any of the source MaybeSources signal an onError or onComplete. This also means it is possible some sources may not get subscribed to at all.
 
 Scheduler:
 
 zip does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T1 - the value type of the first source
 
 T2 - the value type of the second source
 
 T3 - the value type of the third source
 
 T4 - the value type of the fourth source
 
 T5 - the value type of the fifth source
 
 R - the zipped result type
 
 Parameters:
 
 source1 - the first source MaybeSource
 
 source2 - a second source MaybeSource
 
 source3 - a third source MaybeSource
 
 source4 - a fourth source MaybeSource
 
 source5 - a fifth source MaybeSource
 
 zipper - a function that, when applied to an item emitted by each of the source MaybeSources, results in an item that will be emitted by the resulting Maybe
 
 Returns:
 
 a Maybe that emits the zipped results
 
 See Also:
 
 ReactiveX operators documentation: Zip
 - zip
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T1,T2,T3,T4,T5,T6,R> @NonNull Maybe<R> zip(@NonNull @NonNull MaybeSource<? extends T1> source1,
 @NonNull @NonNull MaybeSource<? extends T2> source2,
 @NonNull @NonNull MaybeSource<? extends T3> source3,
 @NonNull @NonNull MaybeSource<? extends T4> source4,
 @NonNull @NonNull MaybeSource<? extends T5> source5,
 @NonNull @NonNull MaybeSource<? extends T6> source6,
 @NonNull @NonNull Function6<? super T1,? super T2,? super T3,? super T4,? super T5,? super T6,? extends R> zipper)
```
 Returns a Maybe that emits the results of a specified combiner function applied to combinations of six items emitted, in sequence, by six other MaybeSources.
 
 This operator terminates eagerly if any of the source MaybeSources signal an onError or onComplete. This also means it is possible some sources may not get subscribed to at all.
 
 Scheduler:
 
 zip does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T1 - the value type of the first source
 
 T2 - the value type of the second source
 
 T3 - the value type of the third source
 
 T4 - the value type of the fourth source
 
 T5 - the value type of the fifth source
 
 T6 - the value type of the sixth source
 
 R - the zipped result type
 
 Parameters:
 
 source1 - the first source MaybeSource
 
 source2 - a second source MaybeSource
 
 source3 - a third source MaybeSource
 
 source4 - a fourth source MaybeSource
 
 source5 - a fifth source MaybeSource
 
 source6 - a sixth source MaybeSource
 
 zipper - a function that, when applied to an item emitted by each of the source MaybeSources, results in an item that will be emitted by the resulting Maybe
 
 Returns:
 
 a Maybe that emits the zipped results
 
 See Also:
 
 ReactiveX operators documentation: Zip
 - zip
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T1,T2,T3,T4,T5,T6,T7,R> @NonNull Maybe<R> zip(@NonNull @NonNull MaybeSource<? extends T1> source1,
 @NonNull @NonNull MaybeSource<? extends T2> source2,
 @NonNull @NonNull MaybeSource<? extends T3> source3,
 @NonNull @NonNull MaybeSource<? extends T4> source4,
 @NonNull @NonNull MaybeSource<? extends T5> source5,
 @NonNull @NonNull MaybeSource<? extends T6> source6,
 @NonNull @NonNull MaybeSource<? extends T7> source7,
 @NonNull @NonNull Function7<? super T1,? super T2,? super T3,? super T4,? super T5,? super T6,? super T7,? extends R> zipper)
```
 Returns a Maybe that emits the results of a specified combiner function applied to combinations of seven items emitted, in sequence, by seven other MaybeSources.
 
 This operator terminates eagerly if any of the source MaybeSources signal an onError or onComplete. This also means it is possible some sources may not get subscribed to at all.
 
 Scheduler:
 
 zip does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T1 - the value type of the first source
 
 T2 - the value type of the second source
 
 T3 - the value type of the third source
 
 T4 - the value type of the fourth source
 
 T5 - the value type of the fifth source
 
 T6 - the value type of the sixth source
 
 T7 - the value type of the seventh source
 
 R - the zipped result type
 
 Parameters:
 
 source1 - the first source MaybeSource
 
 source2 - a second source MaybeSource
 
 source3 - a third source MaybeSource
 
 source4 - a fourth source MaybeSource
 
 source5 - a fifth source MaybeSource
 
 source6 - a sixth source MaybeSource
 
 source7 - a seventh source MaybeSource
 
 zipper - a function that, when applied to an item emitted by each of the source MaybeSources, results in an item that will be emitted by the resulting Maybe
 
 Returns:
 
 a Maybe that emits the zipped results
 
 See Also:
 
 ReactiveX operators documentation: Zip
 - zip
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T1,T2,T3,T4,T5,T6,T7,T8,R> @NonNull Maybe<R> zip(@NonNull @NonNull MaybeSource<? extends T1> source1,
 @NonNull @NonNull MaybeSource<? extends T2> source2,
 @NonNull @NonNull MaybeSource<? extends T3> source3,
 @NonNull @NonNull MaybeSource<? extends T4> source4,
 @NonNull @NonNull MaybeSource<? extends T5> source5,
 @NonNull @NonNull MaybeSource<? extends T6> source6,
 @NonNull @NonNull MaybeSource<? extends T7> source7,
 @NonNull @NonNull MaybeSource<? extends T8> source8,
 @NonNull @NonNull Function8<? super T1,? super T2,? super T3,? super T4,? super T5,? super T6,? super T7,? super T8,? extends R> zipper)
```
 Returns a Maybe that emits the results of a specified combiner function applied to combinations of eight items emitted, in sequence, by eight other MaybeSources.
 
 This operator terminates eagerly if any of the source MaybeSources signal an onError or onComplete. This also means it is possible some sources may not get subscribed to at all.
 
 Scheduler:
 
 zip does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T1 - the value type of the first source
 
 T2 - the value type of the second source
 
 T3 - the value type of the third source
 
 T4 - the value type of the fourth source
 
 T5 - the value type of the fifth source
 
 T6 - the value type of the sixth source
 
 T7 - the value type of the seventh source
 
 T8 - the value type of the eighth source
 
 R - the zipped result type
 
 Parameters:
 
 source1 - the first source MaybeSource
 
 source2 - a second source MaybeSource
 
 source3 - a third source MaybeSource
 
 source4 - a fourth source MaybeSource
 
 source5 - a fifth source MaybeSource
 
 source6 - a sixth source MaybeSource
 
 source7 - a seventh source MaybeSource
 
 source8 - an eighth source MaybeSource
 
 zipper - a function that, when applied to an item emitted by each of the source MaybeSources, results in an item that will be emitted by the resulting Maybe
 
 Returns:
 
 a Maybe that emits the zipped results
 
 See Also:
 
 ReactiveX operators documentation: Zip
 - zip
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public static <T1,T2,T3,T4,T5,T6,T7,T8,T9,R> @NonNull Maybe<R> zip(@NonNull @NonNull MaybeSource<? extends T1> source1,
 @NonNull @NonNull MaybeSource<? extends T2> source2,
 @NonNull @NonNull MaybeSource<? extends T3> source3,
 @NonNull @NonNull MaybeSource<? extends T4> source4,
 @NonNull @NonNull MaybeSource<? extends T5> source5,
 @NonNull @NonNull MaybeSource<? extends T6> source6,
 @NonNull @NonNull MaybeSource<? extends T7> source7,
 @NonNull @NonNull MaybeSource<? extends T8> source8,
 @NonNull @NonNull MaybeSource<? extends T9> source9,
 @NonNull @NonNull Function9<? super T1,? super T2,? super T3,? super T4,? super T5,? super T6,? super T7,? super T8,? super T9,? extends R> zipper)
```
 Returns a Maybe that emits the results of a specified combiner function applied to combinations of nine items emitted, in sequence, by nine other MaybeSources.
 
 This operator terminates eagerly if any of the source MaybeSources signal an onError or onComplete. This also means it is possible some sources may not get subscribed to at all.
 
 Scheduler:
 
 zip does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T1 - the value type of the first source
 
 T2 - the value type of the second source
 
 T3 - the value type of the third source
 
 T4 - the value type of the fourth source
 
 T5 - the value type of the fifth source
 
 T6 - the value type of the sixth source
 
 T7 - the value type of the seventh source
 
 T8 - the value type of the eighth source
 
 T9 - the value type of the ninth source
 
 R - the zipped result type
 
 Parameters:
 
 source1 - the first source MaybeSource
 
 source2 - a second source MaybeSource
 
 source3 - a third source MaybeSource
 
 source4 - a fourth source MaybeSource
 
 source5 - a fifth source MaybeSource
 
 source6 - a sixth source MaybeSource
 
 source7 - a seventh source MaybeSource
 
 source8 - an eighth source MaybeSource
 
 source9 - a ninth source MaybeSource
 
 zipper - a function that, when applied to an item emitted by each of the source MaybeSources, results in an item that will be emitted by the resulting MaybeSource
 
 Returns:
 
 a Maybe that emits the zipped results
 
 See Also:
 
 ReactiveX operators documentation: Zip
 - zipArray
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
 @SafeVarargs
public static <T,R> @NonNull Maybe<R> zipArray(@NonNull @NonNull Function<? super Object[],? extends R> zipper,
 @NonNull MaybeSource<? extends T>... sources)
```
 Returns a Maybe that emits the results of a specified combiner function applied to combinations of items emitted, in sequence, by an array of other MaybeSources.
 Note on method signature: since Java doesn't allow creating a generic array with new T[], the implementation of this operator has to create an Object[] instead. Unfortunately, a Function<Integer[], R> passed to the method would trigger a ClassCastException.
 
 This operator terminates eagerly if any of the source MaybeSources signal an onError or onComplete. This also means it is possible some sources may not get subscribed to at all.
 
 Scheduler:
 
 zipArray does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 T - the common element type
 
 R - the result type
 
 Parameters:
 
 sources - an array of source MaybeSources
 
 zipper - a function that, when applied to an item emitted by each of the source MaybeSources, results in an item that will be emitted by the resulting MaybeSource
 
 Returns:
 
 a Maybe that emits the zipped results
 
 See Also:
 
 ReactiveX operators documentation: Zip
 - ambWith
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> ambWith(@NonNull @NonNull MaybeSource<? extends T> other)
```
 Mirrors the MaybeSource (current or provided) that first signals an event.
 
 Scheduler:
 
 ambWith does not operate by default on a particular Scheduler.
 
 Parameters:
 
 other - a MaybeSource competing to react first. A subscription to this provided source will occur after subscribing to the current source.
 
 Returns:
 
 a Maybe that emits the same sequence as whichever of the source MaybeSources first signalled
 
 See Also:
 
 ReactiveX operators documentation: Amb
 - blockingGet
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @Nullable
public final T blockingGet()
```
 Waits in a blocking fashion until the current Maybe signals a success value (which is returned), null if completed or an exception (which is propagated).
 
 Scheduler:
 
 blockingGet does not operate by default on a particular Scheduler.
 
 Error handling:
 
 If the source signals an error, the operator wraps a checked Exception into RuntimeException and throws that. Otherwise, RuntimeExceptions and Errors are rethrown as they are.
 
 Returns:
 
 the success value
 - blockingGet
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @Nullable
public final T blockingGet(@Nullable T defaultValue)
```
 Waits in a blocking fashion until the current Maybe signals a success value (which is returned), defaultValue if completed or an exception (which is propagated).
 
 Scheduler:
 
 blockingGet does not operate by default on a particular Scheduler.
 
 Error handling:
 
 If the source signals an error, the operator wraps a checked Exception into RuntimeException and throws that. Otherwise, RuntimeExceptions and Errors are rethrown as they are.
 
 Parameters:
 
 defaultValue - the default item to return if this Maybe is empty
 
 Returns:
 
 the success value
 - cache
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Maybe<T> cache()
```
 Returns a Maybe that subscribes to this Maybe lazily, caches its event and replays it, to all the downstream subscribers.
 
 The operator subscribes only when the first downstream subscriber subscribes and maintains a single subscription towards this Maybe.
 Note: You sacrifice the ability to dispose the origin when you use the cache.
 
 Scheduler:
 
 cache does not operate by default on a particular Scheduler.
 
 Returns:
 
 a Maybe that, when first subscribed to, caches all of its items and notifications for the benefit of subsequent subscribers
 
 See Also:
 
 ReactiveX operators documentation: Replay
 - cast
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final  @NonNull Maybe cast(@NonNull @NonNull Class<? extends U> clazz)
```
 Casts the success value of the current Maybe into the target type or signals a ClassCastException if not compatible.
 
 Scheduler:
 
 cast does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 U - the target type
 
 Parameters:
 
 clazz - the type token to use for casting the success result from the current Maybe
 
 Returns:
 
 the new Maybe instance
 - compose
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final <R> @NonNull Maybe<R> compose(@NonNull @NonNull MaybeTransformer<? super T,? extends R> transformer)
```
 Transform a Maybe by applying a particular Transformer function to it.
 This method operates on the Maybe itself whereas lift(io.reactivex.rxjava3.core.MaybeOperator<? extends R, ? super T>) operates on the Maybe's MaybeObservers.
 If the operator you are creating is designed to act on the individual item emitted by a Maybe, use lift(io.reactivex.rxjava3.core.MaybeOperator<? extends R, ? super T>). If your operator is designed to transform the source Maybe as a whole (for instance, by applying a particular set of existing RxJava operators to it) use compose.
 
 Scheduler:
 
 compose does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 R - the value type of the Maybe returned by the transformer function
 
 Parameters:
 
 transformer - the transformer function, not null
 
 Returns:
 
 a Maybe, transformed by the transformer function
 
 See Also:
 
 RxJava wiki: Implementing Your Own Operators
 - concatMap
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final <R> @NonNull Maybe<R> concatMap(@NonNull @NonNull Function<? super T,? extends MaybeSource<? extends R>> mapper)
```
 Returns a Maybe that is based on applying a specified function to the item emitted by the source Maybe, where that function returns a MaybeSource.
 
 Scheduler:
 
 concatMap does not operate by default on a particular Scheduler.
 
 Note that flatMap and concatMap for Maybe is the same operation.
 
 Type Parameters:
 
 R - the result value type
 
 Parameters:
 
 mapper - a function that, when applied to the item emitted by the source Maybe, returns a MaybeSource
 
 Returns:
 
 the Maybe returned from func when applied to the item emitted by the source Maybe
 
 See Also:
 
 ReactiveX operators documentation: FlatMap
 - concatWith
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Flowable<T> concatWith(@NonNull @NonNull MaybeSource<? extends T> other)
```
 Returns a Flowable that emits the items emitted from the current MaybeSource, then the next, one after the other, without interleaving them.
 
 Backpressure:
 
 The operator honors backpressure from downstream.
 
 Scheduler:
 
 concatWith does not operate by default on a particular Scheduler.
 
 Parameters:
 
 other - a MaybeSource to be concatenated after the current
 
 Returns:
 
 a Flowable that emits items emitted by the two source MaybeSources, one after the other, without interleaving them
 
 See Also:
 
 ReactiveX operators documentation: Concat
 - contains
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Single<Boolean> contains(@NonNull @NonNull Object item)
```
 Returns a Single that emits a Boolean that indicates whether the source Maybe emitted a specified item.
 
 Scheduler:
 
 contains does not operate by default on a particular Scheduler.
 
 Parameters:
 
 item - the item to search for in the emissions from the source Maybe, not null
 
 Returns:
 
 a Single that emits true if the specified item is emitted by the source Maybe, or false if the source Maybe completes without emitting that item
 
 See Also:
 
 ReactiveX operators documentation: Contains
 - count
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Single<Long> count()
```
 Returns a Single that counts the total number of items emitted (0 or 1) by the source Maybe and emits this count as a 64-bit Long.
 
 Scheduler:
 
 count does not operate by default on a particular Scheduler.
 
 Returns:
 
 a Single that emits a single item: the number of items emitted by the source Maybe as a 64-bit Long item
 
 See Also:
 
 ReactiveX operators documentation: Count
 - defaultIfEmpty
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Single<T> defaultIfEmpty(@NonNull T defaultItem)
```
 Returns a Single that emits the item emitted by the source Maybe or a specified default item if the source Maybe is empty.
 
 Scheduler:
 
 defaultIfEmpty does not operate by default on a particular Scheduler.
 
 Parameters:
 
 defaultItem - the item to emit if the source Maybe emits no items
 
 Returns:
 
 a Single that emits either the specified default item if the source Maybe emits no item, or the item emitted by the source Maybe
 
 See Also:
 
 ReactiveX operators documentation: DefaultIfEmpty
 - delay
```
@CheckReturnValue
 @SchedulerSupport(value="io.reactivex:computation")
 @NonNull
public final @NonNull Maybe<T> delay(long delay,
 @NonNull @NonNull TimeUnit unit)
```
 Returns a Maybe that signals the events emitted by the source Maybe shifted forward in time by a specified delay.
 
 Scheduler:
 
 This version of delay operates by default on the computation Scheduler.
 
 Parameters:
 
 delay - the delay to shift the source by
 
 unit - the TimeUnit in which period is defined
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: Delay, delay(long, TimeUnit, Scheduler)
 - delay
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="custom")
public final @NonNull Maybe<T> delay(long delay,
 @NonNull @NonNull TimeUnit unit,
 @NonNull @NonNull Scheduler scheduler)
```
 Returns a Maybe that signals the events emitted by the source Maybe shifted forward in time by a specified delay running on the specified Scheduler.
 
 Scheduler:
 
 you specify which Scheduler this operator will use.
 
 Parameters:
 
 delay - the delay to shift the source by
 
 unit - the time unit of delay
 
 scheduler - the Scheduler to use for delaying
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: Delay
 - delay
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
 @BackpressureSupport(value=UNBOUNDED_IN)
public final  @NonNull Maybe<T> delay(@NonNull @NonNull Publisher delayIndicator)
```
 Delays the emission of this Maybe until the given Publisher signals an item or completes.
 
 Backpressure:
 
 The delayIndicator is consumed in an unbounded manner but is cancelled after the first item it produces.
 
 Scheduler:
 
 This version of delay does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 U - the subscription delay value type (ignored)
 
 Parameters:
 
 delayIndicator - the Publisher that gets subscribed to when this Maybe signals an event and that signal is emitted when the Publisher signals an item or completes
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: Delay
 - delaySubscription
```
@BackpressureSupport(value=UNBOUNDED_IN)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final  @NonNull Maybe<T> delaySubscription(@NonNull @NonNull Publisher subscriptionIndicator)
```
 Returns a Maybe that delays the subscription to this Maybe until the other Publisher emits an element or completes normally.
 
 Backpressure:
 
 The Publisher source is consumed in an unbounded fashion (without applying backpressure).
 
 Scheduler:
 
 This method does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 U - the value type of the other Publisher, irrelevant
 
 Parameters:
 
 subscriptionIndicator - the other Publisher that should trigger the subscription to this Publisher.
 
 Returns:
 
 a Maybe that delays the subscription to this Maybe until the other Publisher emits an element or completes normally.
 - delaySubscription
```
@CheckReturnValue
 @SchedulerSupport(value="io.reactivex:computation")
 @NonNull
public final @NonNull Maybe<T> delaySubscription(long delay,
 @NonNull @NonNull TimeUnit unit)
```
 Returns a Maybe that delays the subscription to the source Maybe by a given amount of time.
 
 Scheduler:
 
 This version of delaySubscription operates by default on the computation Scheduler.
 
 Parameters:
 
 delay - the time to delay the subscription
 
 unit - the time unit of delay
 
 Returns:
 
 a Maybe that delays the subscription to the source Maybe by the given amount
 
 See Also:
 
 ReactiveX operators documentation: Delay, delaySubscription(long, TimeUnit, Scheduler)
 - delaySubscription
```
@CheckReturnValue
 @SchedulerSupport(value="custom")
 @NonNull
public final @NonNull Maybe<T> delaySubscription(long delay,
 @NonNull @NonNull TimeUnit unit,
 @NonNull @NonNull Scheduler scheduler)
```
 Returns a Maybe that delays the subscription to the source Maybe by a given amount of time, both waiting and subscribing on a given Scheduler.
 
 Scheduler:
 
 You specify which Scheduler this operator will use.
 
 Parameters:
 
 delay - the time to delay the subscription
 
 unit - the time unit of delay
 
 scheduler - the Scheduler on which the waiting and subscription will happen
 
 Returns:
 
 a Maybe that delays the subscription to the source Maybe by a given amount, waiting and subscribing on the given Scheduler
 
 See Also:
 
 ReactiveX operators documentation: Delay
 - doAfterSuccess
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> doAfterSuccess(@NonNull @NonNull Consumer<? super T> onAfterSuccess)
```
 Calls the specified consumer with the success item after this item has been emitted to the downstream.
 Note that the onAfterNext action is shared between subscriptions and as such should be thread-safe.
 
 Scheduler:
 
 doAfterSuccess does not operate by default on a particular Scheduler.
 
 History: 2.0.1 - experimental
 
 Parameters:
 
 onAfterSuccess - the Consumer that will be called after emitting an item from upstream to the downstream
 
 Returns:
 
 the new Maybe instance
 
 Since:
 
 2.1
 - doAfterTerminate
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> doAfterTerminate(@NonNull @NonNull Action onAfterTerminate)
```
 Registers an Action to be called when this Maybe invokes either onSuccess, onComplete or onError.
 
 Scheduler:
 
 doAfterTerminate does not operate by default on a particular Scheduler.
 
 Parameters:
 
 onAfterTerminate - an Action to be invoked when the source Maybe finishes
 
 Returns:
 
 a Maybe that emits the same items as the source Maybe, then invokes the Action
 
 See Also:
 
 ReactiveX operators documentation: Do
 - doFinally
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> doFinally(@NonNull @NonNull Action onFinally)
```
 Calls the specified action after this Maybe signals onSuccess, onError or onComplete or gets disposed by the downstream.
 In case of a race between a terminal event and a dispose call, the provided onFinally action is executed once per subscription.
 Note that the onFinally action is shared between subscriptions and as such should be thread-safe.
 
 Scheduler:
 
 doFinally does not operate by default on a particular Scheduler.
 
 History: 2.0.1 - experimental
 
 Parameters:
 
 onFinally - the action called when this Maybe terminates or gets disposed
 
 Returns:
 
 the new Maybe instance
 
 Since:
 
 2.1
 - doOnDispose
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> doOnDispose(@NonNull @NonNull Action onDispose)
```
 Calls the shared Action if a MaybeObserver subscribed to the current Maybe disposes the common Disposable it received via onSubscribe.
 
 Scheduler:
 
 doOnDispose does not operate by default on a particular Scheduler.
 
 Parameters:
 
 onDispose - the action called when the subscription is disposed
 
 Returns:
 
 the new Maybe instance
 
 Throws:
 
 NullPointerException - if onDispose is null
 - doOnComplete
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> doOnComplete(@NonNull @NonNull Action onComplete)
```
 Modifies the source Maybe so that it invokes an action when it calls onComplete.
 
 Scheduler:
 
 doOnComplete does not operate by default on a particular Scheduler.
 
 Parameters:
 
 onComplete - the action to invoke when the source Maybe calls onComplete
 
 Returns:
 
 the new Maybe with the side-effecting behavior applied
 
 See Also:
 
 ReactiveX operators documentation: Do
 - doOnError
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> doOnError(@NonNull @NonNull Consumer<? super Throwable> onError)
```
 Calls the shared consumer with the error sent via onError for each MaybeObserver that subscribes to the current Maybe.
 
 Scheduler:
 
 doOnError does not operate by default on a particular Scheduler.
 
 Parameters:
 
 onError - the consumer called with the success value of onError
 
 Returns:
 
 the new Maybe instance
 - doOnEvent
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Maybe<T> doOnEvent(@NonNull @NonNull BiConsumer<? super T,? super Throwable> onEvent)
```
 Calls the given onEvent callback with the (success value, null) for an onSuccess, (null, throwable) for an onError or (null, null) for an onComplete signal from this Maybe before delivering said signal to the downstream.
 
 Exceptions thrown from the callback will override the event so the downstream receives the error instead of the original signal.
 
 Scheduler:
 
 doOnEvent does not operate by default on a particular Scheduler.
 
 Parameters:
 
 onEvent - the callback to call with the terminal event tuple
 
 Returns:
 
 the new Maybe instance
 - doOnSubscribe
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> doOnSubscribe(@NonNull @NonNull Consumer<? super Disposable> onSubscribe)
```
 Calls the shared consumer with the Disposable sent through the onSubscribe for each MaybeObserver that subscribes to the current Maybe.
 
 Scheduler:
 
 doOnSubscribe does not operate by default on a particular Scheduler.
 
 Parameters:
 
 onSubscribe - the consumer called with the Disposable sent via onSubscribe
 
 Returns:
 
 the new Maybe instance
 - doOnTerminate
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> doOnTerminate(@NonNull @NonNull Action onTerminate)
```
 Returns a Maybe instance that calls the given onTerminate callback just before this Maybe completes normally or with an exception.
 
 This differs from doAfterTerminate in that this happens before the onComplete or onError notification.
 
 Scheduler:
 
 doOnTerminate does not operate by default on a particular Scheduler.
 
 History: 2.2.7 - experimental
 
 Parameters:
 
 onTerminate - the action to invoke when the consumer calls onComplete or onError
 
 Returns:
 
 the new Maybe instance
 
 Since:
 
 3.0.0
 
 See Also:
 
 ReactiveX operators documentation: Do, doOnTerminate(Action)
 - doOnSuccess
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> doOnSuccess(@NonNull @NonNull Consumer<? super T> onSuccess)
```
 Calls the shared consumer with the success value sent via onSuccess for each MaybeObserver that subscribes to the current Maybe.
 
 Scheduler:
 
 doOnSuccess does not operate by default on a particular Scheduler.
 
 Parameters:
 
 onSuccess - the consumer called with the success value of onSuccess
 
 Returns:
 
 the new Maybe instance
 - filter
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> filter(@NonNull @NonNull Predicate<? super T> predicate)
```
 Filters the success item of the Maybe via a predicate function and emitting it if the predicate returns true, completing otherwise.
 
 Scheduler:
 
 filter does not operate by default on a particular Scheduler.
 
 Parameters:
 
 predicate - a function that evaluates the item emitted by the source Maybe, returning true if it passes the filter
 
 Returns:
 
 a Maybe that emit the item emitted by the source Maybe that the filter evaluates as true
 
 See Also:
 
 ReactiveX operators documentation: Filter
 - flatMap
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final <R> @NonNull Maybe<R> flatMap(@NonNull @NonNull Function<? super T,? extends MaybeSource<? extends R>> mapper)
```
 Returns a Maybe that is based on applying a specified function to the item emitted by the source Maybe, where that function returns a MaybeSource.
 
 Scheduler:
 
 flatMap does not operate by default on a particular Scheduler.
 
 Note that flatMap and concatMap for Maybe is the same operation.
 
 Type Parameters:
 
 R - the result value type
 
 Parameters:
 
 mapper - a function that, when applied to the item emitted by the source Maybe, returns a MaybeSource
 
 Returns:
 
 the Maybe returned from func when applied to the item emitted by the source Maybe
 
 See Also:
 
 ReactiveX operators documentation: FlatMap
 - flatMap
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final <R> @NonNull Maybe<R> flatMap(@NonNull @NonNull Function<? super T,? extends MaybeSource<? extends R>> onSuccessMapper,
 @NonNull @NonNull Function<? super Throwable,? extends MaybeSource<? extends R>> onErrorMapper,
 @NonNull @NonNull Supplier<? extends MaybeSource<? extends R>> onCompleteSupplier)
```
 Maps the onSuccess, onError or onComplete signals of this Maybe into MaybeSource and emits that MaybeSource's signals.
 
 Scheduler:
 
 flatMap does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 R - the result type
 
 Parameters:
 
 onSuccessMapper - a function that returns a MaybeSource to merge for the onSuccess item emitted by this Maybe
 
 onErrorMapper - a function that returns a MaybeSource to merge for an onError notification from this Maybe
 
 onCompleteSupplier - a function that returns a MaybeSource to merge for an onComplete notification this Maybe
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: FlatMap
 - flatMap
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final <U,R> @NonNull Maybe<R> flatMap(@NonNull @NonNull Function<? super T,? extends MaybeSource<? extends U>> mapper,
 @NonNull @NonNull BiFunction<? super T,? super U,? extends R> resultSelector)
```
 Returns a Maybe that emits the results of a specified function to the pair of values emitted by the source Maybe and a specified mapped MaybeSource.
 
 Scheduler:
 
 flatMap does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 U - the type of items emitted by the MaybeSource returned by the mapper function
 
 R - the type of items emitted by the resulting Maybe
 
 Parameters:
 
 mapper - a function that returns a MaybeSource for the item emitted by the source Maybe
 
 resultSelector - a function that combines one item emitted by each of the source and collection MaybeSource and returns an item to be emitted by the resulting MaybeSource
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: FlatMap
 - flattenAsFlowable
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final  @NonNull Flowable flattenAsFlowable(@NonNull @NonNull Function<? super T,? extends Iterable<? extends U>> mapper)
```
 Maps the success value of the upstream Maybe into an Iterable and emits its items as a Flowable sequence.
 
 Backpressure:
 
 The operator honors backpressure from downstream.
 
 Scheduler:
 
 flattenAsFlowable does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 U - the type of item emitted by the resulting Iterable
 
 Parameters:
 
 mapper - a function that returns an Iterable sequence of values for when given an item emitted by the source Maybe
 
 Returns:
 
 the new Flowable instance
 
 See Also:
 
 ReactiveX operators documentation: FlatMap, flattenStreamAsFlowable(Function)
 - flattenAsObservable
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final  @NonNull Observable flattenAsObservable(@NonNull @NonNull Function<? super T,? extends Iterable<? extends U>> mapper)
```
 Maps the success value of the upstream Maybe into an Iterable and emits its items as an Observable sequence.
 
 Scheduler:
 
 flattenAsObservable does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 U - the type of item emitted by the resulting Iterable
 
 Parameters:
 
 mapper - a function that returns an Iterable sequence of values for when given an item emitted by the source Maybe
 
 Returns:
 
 the new Observable instance
 
 See Also:
 
 ReactiveX operators documentation: FlatMap
 - flatMapObservable
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final <R> @NonNull Observable<R> flatMapObservable(@NonNull @NonNull Function<? super T,? extends ObservableSource<? extends R>> mapper)
```
 Returns an Observable that is based on applying a specified function to the item emitted by the source Maybe, where that function returns an ObservableSource.
 
 Scheduler:
 
 flatMapObservable does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 R - the result value type
 
 Parameters:
 
 mapper - a function that, when applied to the item emitted by the source Maybe, returns an ObservableSource
 
 Returns:
 
 the Observable returned from func when applied to the item emitted by the source Maybe
 
 See Also:
 
 ReactiveX operators documentation: FlatMap
 - flatMapPublisher
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final <R> @NonNull Flowable<R> flatMapPublisher(@NonNull @NonNull Function<? super T,? extends Publisher<? extends R>> mapper)
```
 Returns a Flowable that emits items based on applying a specified function to the item emitted by the source Maybe, where that function returns a Publisher.
 
 Backpressure:
 
 The returned Flowable honors the downstream backpressure.
 
 Scheduler:
 
 flatMapPublisher does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 R - the result value type
 
 Parameters:
 
 mapper - a function that, when applied to the item emitted by the source Maybe, returns a Flowable
 
 Returns:
 
 the Flowable returned from func when applied to the item emitted by the source Maybe
 
 See Also:
 
 ReactiveX operators documentation: FlatMap
 - flatMapSingle
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final <R> @NonNull Single<R> flatMapSingle(@NonNull @NonNull Function<? super T,? extends SingleSource<? extends R>> mapper)
```
 Returns a Single based on applying a specified function to the item emitted by the source Maybe, where that function returns a Single. When this Maybe completes a NoSuchElementException will be thrown.
 
 Scheduler:
 
 flatMapSingle does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 R - the result value type
 
 Parameters:
 
 mapper - a function that, when applied to the item emitted by the source Maybe, returns a Single
 
 Returns:
 
 the Single returned from mapper when applied to the item emitted by the source Maybe
 
 See Also:
 
 ReactiveX operators documentation: FlatMap
 - flatMapSingleElement
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final <R> @NonNull Maybe<R> flatMapSingleElement(@NonNull @NonNull Function<? super T,? extends SingleSource<? extends R>> mapper)
```
 Returns a Maybe based on applying a specified function to the item emitted by the source Maybe, where that function returns a Single. When this Maybe just completes the resulting Maybe completes as well.
 
 Scheduler:
 
 flatMapSingleElement does not operate by default on a particular Scheduler.
 
 History: 2.0.2 - experimental
 
 Type Parameters:
 
 R - the result value type
 
 Parameters:
 
 mapper - a function that, when applied to the item emitted by the source Maybe, returns a Single
 
 Returns:
 
 the new Maybe instance
 
 Since:
 
 2.1
 
 See Also:
 
 ReactiveX operators documentation: FlatMap
 - flatMapCompletable
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Completable flatMapCompletable(@NonNull @NonNull Function<? super T,? extends CompletableSource> mapper)
```
 Returns a Completable that completes based on applying a specified function to the item emitted by the source Maybe, where that function returns a Completable.
 
 Scheduler:
 
 flatMapCompletable does not operate by default on a particular Scheduler.
 
 Parameters:
 
 mapper - a function that, when applied to the item emitted by the source Maybe, returns a Completable
 
 Returns:
 
 the Completable returned from mapper when applied to the item emitted by the source Maybe
 
 See Also:
 
 ReactiveX operators documentation: FlatMap
 - hide
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Maybe<T> hide()
```
 Hides the identity of this Maybe and its Disposable.
 
 Allows preventing certain identity-based optimizations (fusion).
 
 Scheduler:
 
 hide does not operate by default on a particular Scheduler.
 
 Returns:
 
 the new Maybe instance
 - ignoreElement
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Completable ignoreElement()
```
 Ignores the item emitted by the source Maybe and only calls onComplete or onError.
 
 Scheduler:
 
 ignoreElement does not operate by default on a particular Scheduler.
 
 Returns:
 
 an empty Completable that only calls onComplete or onError, based on which one is called by the source Maybe
 
 See Also:
 
 ReactiveX operators documentation: IgnoreElements
 - isEmpty
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Single<Boolean> isEmpty()
```
 Returns a Single that emits true if the source Maybe is empty, otherwise false.
 
 Scheduler:
 
 isEmpty does not operate by default on a particular Scheduler.
 
 Returns:
 
 a Single that emits a Boolean
 
 See Also:
 
 ReactiveX operators documentation: Contains
 - lift
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final <R> @NonNull Maybe<R> lift(@NonNull @NonNull MaybeOperator<? extends R,? super T> lift)
```
 This method requires advanced knowledge about building operators, please consider other standard composition methods first; Returns a Maybe which, when subscribed to, invokes the apply(MaybeObserver) method of the provided MaybeOperator for each individual downstream Maybe and allows the insertion of a custom operator by accessing the downstream's MaybeObserver during this subscription phase and providing a new MaybeObserver, containing the custom operator's intended business logic, that will be used in the subscription process going further upstream.
 
 Generally, such a new MaybeObserver will wrap the downstream's MaybeObserver and forwards the onSuccess, onError and onComplete events from the upstream directly or according to the emission pattern the custom operator's business logic requires. In addition, such operator can intercept the flow control calls of dispose and isDisposed that would have traveled upstream and perform additional actions depending on the same business logic requirements.
 Example:
```
 // Step 1: Create the consumer type that will be returned by the MaybeOperator.apply():
 
 public final class CustomMaybeObserver<T> implements MaybeObserver<T>, Disposable {

 // The downstream's MaybeObserver that will receive the onXXX events
 final MaybeObserver<? super String> downstream;

 // The connection to the upstream source that will call this class' onXXX methods
 Disposable upstream;

 // The constructor takes the downstream subscriber and usually any other parameters
 public CustomMaybeObserver(MaybeObserver<? super String> downstream) {
 this.downstream = downstream;
 }

 // In the subscription phase, the upstream sends a Disposable to this class
 // and subsequently this class has to send a Disposable to the downstream.
 // Note that relaying the upstream's Disposable directly is not allowed in RxJava
 @Override
 public void onSubscribe(Disposable d) {
 if (upstream != null) {
 d.dispose();
 } else {
 upstream = d;
 downstream.onSubscribe(this);
 }
 }

 // The upstream calls this with the next item and the implementation's
 // responsibility is to emit an item to the downstream based on the intended
 // business logic, or if it can't do so for the particular item,
 // request more from the upstream
 @Override
 public void onSuccess(T item) {
 String str = item.toString();
 if (str.length() < 2) {
 downstream.onSuccess(str);
 } else {
 // Maybe is usually expected to produce one of the onXXX events
 downstream.onComplete();
 }
 }

 // Some operators may handle the upstream's error while others
 // could just forward it to the downstream.
 @Override
 public void onError(Throwable throwable) {
 downstream.onError(throwable);
 }

 // When the upstream completes, usually the downstream should complete as well.
 @Override
 public void onComplete() {
 downstream.onComplete();
 }

 // Some operators may use their own resources which should be cleaned up if
 // the downstream disposes the flow before it completed. Operators without
 // resources can simply forward the dispose to the upstream.
 // In some cases, a disposed flag may be set by this method so that other parts
 // of this class may detect the dispose and stop sending events
 // to the downstream.
 @Override
 public void dispose() {
 upstream.dispose();
 }

 // Some operators may simply forward the call to the upstream while others
 // can return the disposed flag set in dispose().
 @Override
 public boolean isDisposed() {
 return upstream.isDisposed();
 }
 }

 // Step 2: Create a class that implements the MaybeOperator interface and
 // returns the custom consumer type from above in its apply() method.
 // Such class may define additional parameters to be submitted to
 // the custom consumer type.

 final class CustomMaybeOperator<T> implements MaybeOperator<String> {
 @Override
 public MaybeObserver<? super String> apply(MaybeObserver<? super T> upstream) {
 return new CustomMaybeObserver<T>(upstream);
 }
 }

 // Step 3: Apply the custom operator via lift() in a flow by creating an instance of it
 // or reusing an existing one.

 Maybe.just(5)
 .lift(new CustomMaybeOperator<Integer>())
 .test()
 .assertResult("5");

 Maybe.just(15)
 .lift(new CustomMaybeOperator<Integer>())
 .test()
 .assertResult();
 
```
 Creating custom operators can be complicated and it is recommended one consults the RxJava wiki: Writing operators page about the tools, requirements, rules, considerations and pitfalls of implementing them.
 Note that implementing custom operators via this lift() method adds slightly more overhead by requiring an additional allocation and indirection per assembled flows. Instead, extending the abstract Maybe class and creating a MaybeTransformer with it is recommended.
 Note also that it is not possible to stop the subscription phase in lift() as the apply() method requires a non-null MaybeObserver instance to be returned, which is then unconditionally subscribed to the upstream Maybe. For example, if the operator decided there is no reason to subscribe to the upstream source because of some optimization possibility or a failure to prepare the operator, it still has to return a MaybeObserver that should immediately dispose the upstream's Disposable in its onSubscribe method. Again, using a MaybeTransformer and extending the Maybe is a better option as subscribeActual(io.reactivex.rxjava3.core.MaybeObserver<? super T>) can decide to not subscribe to its upstream after all.
 
 Scheduler:
 
 lift does not operate by default on a particular Scheduler, however, the MaybeOperator may use a Scheduler to support its own asynchronous behavior.
 Type Parameters:
 
 R - the output value type
 
 Parameters:
 
 lift - the MaybeOperator that receives the downstream's MaybeObserver and should return a MaybeObserver with custom behavior to be used as the consumer for the current Maybe.
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 RxJava wiki: Writing operators, compose(MaybeTransformer)
 - map
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final <R> @NonNull Maybe<R> map(@NonNull @NonNull Function<? super T,? extends R> mapper)
```
 Returns a Maybe that applies a specified function to the item emitted by the source Maybe and emits the result of this function application.
 
 Scheduler:
 
 map does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 R - the result value type
 
 Parameters:
 
 mapper - a function to apply to the item emitted by the Maybe
 
 Returns:
 
 a Maybe that emits the item from the source Maybe, transformed by the specified function
 
 See Also:
 
 ReactiveX operators documentation: Map
 - materialize
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Single<Notification<T>> materialize()
```
 Maps the signal types of this Maybe into a Notification of the same kind and emits it as a single success value to downstream.
 
 Scheduler:
 
 materialize does not operate by default on a particular Scheduler.
 
 History: 2.2.4 - experimental
 
 Returns:
 
 the new Single instance
 
 Since:
 
 3.0.0
 
 See Also:
 
 Single.dematerialize(Function)
 - mergeWith
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Flowable<T> mergeWith(@NonNull @NonNull MaybeSource<? extends T> other)
```
 Flattens this and another Maybe into a single Flowable, without any transformation.
 
 You can combine items emitted by multiple Maybes so that they appear as a single Flowable, by using the mergeWith method.
 
 Backpressure:
 
 The operator honors backpressure from downstream.
 
 Scheduler:
 
 mergeWith does not operate by default on a particular Scheduler.
 
 Parameters:
 
 other - a MaybeSource to be merged
 
 Returns:
 
 a new Flowable instance
 
 See Also:
 
 ReactiveX operators documentation: Merge
 - observeOn
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="custom")
public final @NonNull Maybe<T> observeOn(@NonNull @NonNull Scheduler scheduler)
```
 Wraps a Maybe to emit its item (or notify of its error) on a specified Scheduler, asynchronously.
 
 Scheduler:
 
 you specify which Scheduler this operator will use.
 
 Parameters:
 
 scheduler - the Scheduler to notify subscribers on
 
 Returns:
 
 the new Maybe instance that its subscribers are notified on the specified Scheduler
 
 See Also:
 
 ReactiveX operators documentation: ObserveOn, RxJava Threading Examples, subscribeOn(io.reactivex.rxjava3.core.Scheduler)
 - ofType
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final  @NonNull Maybe ofType(@NonNull @NonNull Class clazz)
```
 Filters the items emitted by a Maybe, only emitting its success value if that is an instance of the supplied Class.
 
 Scheduler:
 
 ofType does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 U - the output type
 
 Parameters:
 
 clazz - the class type to filter the items emitted by the source Maybe
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: Filter
 - to
```
@CheckReturnValue
 @SchedulerSupport(value="none")
public final <R> R to(@NonNull @NonNull MaybeConverter<T,? extends R> converter)
```
 Calls the specified converter function during assembly time and returns its resulting value.
 This allows fluent conversion to any other type.
 
 Scheduler:
 
 to does not operate by default on a particular Scheduler.
 
 History: 2.1.7 - experimental
 
 Type Parameters:
 
 R - the resulting object type
 
 Parameters:
 
 converter - the function that receives the current Maybe instance and returns a value
 
 Returns:
 
 the converted value
 
 Throws:
 
 NullPointerException - if converter is null
 
 Since:
 
 2.2
 - toFlowable
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Flowable<T> toFlowable()
```
 Converts this Maybe into a backpressure-aware Flowable instance composing cancellation through.
 
 Backpressure:
 
 The returned Flowable honors the backpressure of the downstream.
 
 Scheduler:
 
 toFlowable does not operate by default on a particular Scheduler.
 
 Returns:
 
 the new Flowable instance
 - toObservable
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Observable<T> toObservable()
```
 Converts this Maybe into an Observable instance composing disposal through.
 
 Scheduler:
 
 toObservable does not operate by default on a particular Scheduler.
 
 Returns:
 
 the new Observable instance
 - toSingle
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Single<T> toSingle()
```
 Converts this Maybe into a Single instance composing disposal through and turning an empty Maybe into a signal of NoSuchElementException.
 
 Scheduler:
 
 toSingle does not operate by default on a particular Scheduler.
 
 Returns:
 
 the new Single instance
 - onErrorComplete
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Maybe<T> onErrorComplete()
```
 Returns a Maybe instance that if this Maybe emits an error, it will emit an onComplete and swallow the throwable.
 
 Scheduler:
 
 onErrorComplete does not operate by default on a particular Scheduler.
 
 Returns:
 
 the new Maybe instance
 - onErrorComplete
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> onErrorComplete(@NonNull @NonNull Predicate<? super Throwable> predicate)
```
 Returns a Maybe instance that if this Maybe emits an error and the predicate returns true, it will emit an onComplete and swallow the throwable.
 
 Scheduler:
 
 onErrorComplete does not operate by default on a particular Scheduler.
 
 Parameters:
 
 predicate - the predicate to call when an Throwable is emitted which should return true if the Throwable should be swallowed and replaced with an onComplete.
 
 Returns:
 
 the new Maybe instance
 - onErrorResumeWith
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> onErrorResumeWith(@NonNull @NonNull MaybeSource<? extends T> next)
```
 Instructs a Maybe to pass control to another MaybeSource rather than invoking onError if it encounters an error.
 
 You can use this to prevent errors from propagating or to supply fallback data should errors be encountered.
 
 Scheduler:
 
 onErrorResumeWith does not operate by default on a particular Scheduler.
 
 Parameters:
 
 next - the next MaybeSource that will take over if the source Maybe encounters an error
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: Catch
 - onErrorResumeNext
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> onErrorResumeNext(@NonNull @NonNull Function<? super Throwable,? extends MaybeSource<? extends T>> resumeFunction)
```
 Instructs a Maybe to pass control to another Maybe rather than invoking onError if it encounters an error.
 
 You can use this to prevent errors from propagating or to supply fallback data should errors be encountered.
 
 Scheduler:
 
 onErrorResumeNext does not operate by default on a particular Scheduler.
 
 Parameters:
 
 resumeFunction - a function that returns a MaybeSource that will take over if the source Maybe encounters an error
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: Catch
 - onErrorReturn
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> onErrorReturn(@NonNull @NonNull Function<? super Throwable,? extends T> valueSupplier)
```
 Instructs a Maybe to emit an item (returned by a specified function) rather than invoking onError if it encounters an error.
 
 You can use this to prevent errors from propagating or to supply fallback data should errors be encountered.
 
 Scheduler:
 
 onErrorReturn does not operate by default on a particular Scheduler.
 
 Parameters:
 
 valueSupplier - a function that returns a single value that will be emitted as success value the current Maybe signals an onError event
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: Catch
 - onErrorReturnItem
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> onErrorReturnItem(@NonNull T item)
```
 Instructs a Maybe to emit an item (returned by a specified function) rather than invoking onError if it encounters an error.
 
 You can use this to prevent errors from propagating or to supply fallback data should errors be encountered.
 
 Scheduler:
 
 onErrorReturnItem does not operate by default on a particular Scheduler.
 
 Parameters:
 
 item - the value that is emitted as onSuccess in case this Maybe signals an onError
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: Catch
 - onExceptionResumeNext
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> onExceptionResumeNext(@NonNull @NonNull MaybeSource<? extends T> next)
```
 Instructs a Maybe to pass control to another MaybeSource rather than invoking onError if it encounters an Exception.
 This differs from onErrorResumeNext(io.reactivex.rxjava3.functions.Function<? super java.lang.Throwable, ? extends io.reactivex.rxjava3.core.MaybeSource<? extends T>>) in that this one does not handle Throwable or Error but lets those continue through.
 
 You can use this to prevent exceptions from propagating or to supply fallback data should exceptions be encountered.
 
 Scheduler:
 
 onExceptionResumeNext does not operate by default on a particular Scheduler.
 
 Parameters:
 
 next - the next MaybeSource that will take over if the source Maybe encounters an exception
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: Catch
 - onTerminateDetach
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Maybe<T> onTerminateDetach()
```
 Nulls out references to the upstream producer and downstream MaybeObserver if the sequence is terminated or downstream calls dispose().
 
 Scheduler:
 
 onTerminateDetach does not operate by default on a particular Scheduler.
 
 Returns:
 
 a Maybe which nulls out references to the upstream producer and downstream MaybeObserver if the sequence is terminated or downstream calls dispose()
 - repeat
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Flowable<T> repeat()
```
 Returns a Flowable that repeats the sequence of items emitted by the source Maybe indefinitely.
 
 Backpressure:
 
 The operator honors downstream backpressure.
 
 Scheduler:
 
 repeat does not operate by default on a particular Scheduler.
 
 Returns:
 
 a Flowable that emits the items emitted by the source Maybe repeatedly and in sequence
 
 See Also:
 
 ReactiveX operators documentation: Repeat
 - repeat
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Flowable<T> repeat(long times)
```
 Returns a Flowable that repeats the sequence of items emitted by the source Maybe at most count times.
 
 Backpressure:
 
 This operator honors downstream backpressure.
 
 Scheduler:
 
 repeat does not operate by default on a particular Scheduler.
 
 Parameters:
 
 times - the number of times the source Maybe items are repeated, a count of 0 will yield an empty sequence
 
 Returns:
 
 a Flowable that repeats the sequence of items emitted by the source Maybe at most count times
 
 Throws:
 
 IllegalArgumentException - if count is less than zero
 
 See Also:
 
 ReactiveX operators documentation: Repeat
 - repeatUntil
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Flowable<T> repeatUntil(@NonNull @NonNull BooleanSupplier stop)
```
 Returns a Flowable that repeats the sequence of items emitted by the source Maybe until the provided stop function returns true.
 
 Backpressure:
 
 This operator honors downstream backpressure.
 
 Scheduler:
 
 repeatUntil does not operate by default on a particular Scheduler.
 
 Parameters:
 
 stop - a boolean supplier that is called when the current Flowable completes and unless it returns false, the current Flowable is resubscribed
 
 Returns:
 
 the new Flowable instance
 
 Throws:
 
 NullPointerException - if stop is null
 
 See Also:
 
 ReactiveX operators documentation: Repeat
 - repeatWhen
```
@BackpressureSupport(value=FULL)
 @CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Flowable<T> repeatWhen(@NonNull @NonNull Function<? super Flowable<Object>,? extends Publisher<?>> handler)
```
 Returns a Flowable that emits the same values as the source Publisher with the exception of an onComplete. An onComplete notification from the source will result in the emission of a void item to the Publisher provided as an argument to the notificationHandler function. If that Publisher calls onComplete or onError then repeatWhen will call onComplete or onError on the child subscription. Otherwise, this Publisher will resubscribe to the source Publisher.
 
 Backpressure:
 
 The operator honors downstream backpressure and expects the source Publisher to honor backpressure as well. If this expectation is violated, the operator may throw an IllegalStateException.
 
 Scheduler:
 
 repeatWhen does not operate by default on a particular Scheduler.
 
 Parameters:
 
 handler - receives a Publisher of notifications with which a user can complete or error, aborting the repeat.
 
 Returns:
 
 the source Publisher modified with repeat logic
 
 See Also:
 
 ReactiveX operators documentation: Repeat
 - retry
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Maybe<T> retry()
```
 Returns a Maybe that mirrors the source Maybe, resubscribing to it if it calls onError (infinite retry count).
 
 If the source Maybe calls MaybeObserver.onError(java.lang.Throwable), this method will resubscribe to the source Maybe rather than propagating the onError call.
 
 Scheduler:
 
 retry does not operate by default on a particular Scheduler.
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: Retry
 - retry
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Maybe<T> retry(@NonNull @NonNull BiPredicate<? super Integer,? super Throwable> predicate)
```
 Returns a Maybe that mirrors the source Maybe, resubscribing to it if it calls onError and the predicate returns true for that specific exception and retry count.
 
 Scheduler:
 
 retry does not operate by default on a particular Scheduler.
 
 Parameters:
 
 predicate - the predicate that determines if a resubscription may happen in case of a specific exception and retry count
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 retry(), ReactiveX operators documentation: Retry
 - retry
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Maybe<T> retry(long count)
```
 Returns a Maybe that mirrors the source Maybe, resubscribing to it if it calls onError up to a specified number of retries.
 
 If the source Maybe calls MaybeObserver.onError(java.lang.Throwable), this method will resubscribe to the source Maybe for a maximum of count resubscriptions rather than propagating the onError call.
 
 Scheduler:
 
 retry does not operate by default on a particular Scheduler.
 
 Parameters:
 
 count - the number of times to resubscribe if the current Maybe fails
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: Retry
 - retry
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Maybe<T> retry(long times,
 @NonNull @NonNull Predicate<? super Throwable> predicate)
```
 Retries at most times or until the predicate returns false, whichever happens first.
 
 Scheduler:
 
 retry does not operate by default on a particular Scheduler.
 
 Parameters:
 
 times - the number of times to resubscribe if the current Maybe fails
 
 predicate - the predicate called with the failure Throwable and should return true to trigger a retry.
 
 Returns:
 
 the new Maybe instance
 - retry
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Maybe<T> retry(@NonNull @NonNull Predicate<? super Throwable> predicate)
```
 Retries the current Maybe if it fails and the predicate returns true.
 
 Scheduler:
 
 retry does not operate by default on a particular Scheduler.
 
 Parameters:
 
 predicate - the predicate that receives the failure Throwable and should return true to trigger a retry.
 
 Returns:
 
 the new Maybe instance
 - retryUntil
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> retryUntil(@NonNull @NonNull BooleanSupplier stop)
```
 Retries until the given stop function returns true.
 
 Scheduler:
 
 retryUntil does not operate by default on a particular Scheduler.
 
 Parameters:
 
 stop - the function that should return true to stop retrying
 
 Returns:
 
 the new Maybe instance
 - retryWhen
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Maybe<T> retryWhen(@NonNull @NonNull Function<? super Flowable<Throwable>,? extends Publisher<?>> handler)
```
 Returns a Maybe that emits the same values as the source Maybe with the exception of an onError. An onError notification from the source will result in the emission of a Throwable item to the Publisher provided as an argument to the notificationHandler function. If that Publisher calls onComplete or onError then retry will call onComplete or onError on the child subscription. Otherwise, this Publisher will resubscribe to the source Publisher.
 
 Example: This retries 3 times, each time incrementing the number of seconds it waits.
```
 Maybe.create((MaybeEmitter<? super String> s) -> {
 System.out.println("subscribing");
 s.onError(new RuntimeException("always fails"));
 }, BackpressureStrategy.BUFFER).retryWhen(attempts -> {
 return attempts.zipWith(Publisher.range(1, 3), (n, i) -> i).flatMap(i -> {
 System.out.println("delay retry by " + i + " second(s)");
 return Flowable.timer(i, TimeUnit.SECONDS);
 });
 }).blockingForEach(System.out::println);
 
```
 Output is:
```
 
 subscribing
 delay retry by 1 second(s)
 subscribing
 delay retry by 2 second(s)
 subscribing
 delay retry by 3 second(s)
 subscribing
 
```
 Note that the inner Publisher returned by the handler function should signal either onNext, onError or onComplete in response to the received Throwable to indicate the operator should retry or terminate. If the upstream to the operator is asynchronous, signalling onNext followed by onComplete immediately may result in the sequence to be completed immediately. Similarly, if this inner Publisher signals onError or onComplete while the upstream is active, the sequence is terminated with the same signal immediately.
 The following example demonstrates how to retry an asynchronous source with a delay:
```
 Maybe.timer(1, TimeUnit.SECONDS)
 .doOnSubscribe(s -> System.out.println("subscribing"))
 .map(v -> { throw new RuntimeException(); })
 .retryWhen(errors -> {
 AtomicInteger counter = new AtomicInteger();
 return errors
 .takeWhile(e -> counter.getAndIncrement() != 3)
 .flatMap(e -> {
 System.out.println("delay retry by " + counter.get() + " second(s)");
 return Flowable.timer(counter.get(), TimeUnit.SECONDS);
 });
 })
 .blockingGet();
 
```
 Scheduler:
 
 retryWhen does not operate by default on a particular Scheduler.
 Parameters:
 
 handler - receives a Publisher of notifications with which a user can complete or error, aborting the retry
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: Retry
 - subscribe
```
@SchedulerSupport(value="none")
 @NonNull
public final @NonNull Disposable subscribe()
```
 Subscribes to a Maybe and ignores onSuccess and onComplete emissions.
 If the Maybe emits an error, it is wrapped into an OnErrorNotImplementedException and routed to the RxJavaPlugins.onError handler.
 
 Scheduler:
 
 subscribe does not operate by default on a particular Scheduler.
 
 Returns:
 
 a Disposable reference with which the caller can stop receiving items before the Maybe has finished sending them
 
 See Also:
 
 ReactiveX operators documentation: Subscribe
 - subscribe
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Disposable subscribe(@NonNull @NonNull Consumer<? super T> onSuccess)
```
 Subscribes to a Maybe and provides a callback to handle the items it emits.
 If the Maybe emits an error, it is wrapped into an OnErrorNotImplementedException and routed to the RxJavaPlugins.onError handler.
 
 Scheduler:
 
 subscribe does not operate by default on a particular Scheduler.
 
 Parameters:
 
 onSuccess - the Consumer<T> you have designed to accept a success value from the Maybe
 
 Returns:
 
 a Disposable reference with which the caller can stop receiving items before the Maybe has finished sending them
 
 Throws:
 
 NullPointerException - if onSuccess is null
 
 See Also:
 
 ReactiveX operators documentation: Subscribe
 - subscribe
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull Disposable subscribe(@NonNull @NonNull Consumer<? super T> onSuccess,
 @NonNull @NonNull Consumer<? super Throwable> onError)
```
 Subscribes to a Maybe and provides callbacks to handle the items it emits and any error notification it issues.
 
 Scheduler:
 
 subscribe does not operate by default on a particular Scheduler.
 
 Parameters:
 
 onSuccess - the Consumer<T> you have designed to accept a success value from the Maybe
 
 onError - the Consumer<Throwable> you have designed to accept any error notification from the Maybe
 
 Returns:
 
 a Disposable reference with which the caller can stop receiving items before the Maybe has finished sending them
 
 Throws:
 
 NullPointerException - if onSuccess is null, or if onError is null
 
 See Also:
 
 ReactiveX operators documentation: Subscribe
 - subscribe
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Disposable subscribe(@NonNull @NonNull Consumer<? super T> onSuccess,
 @NonNull @NonNull Consumer<? super Throwable> onError,
 @NonNull @NonNull Action onComplete)
```
 Subscribes to a Maybe and provides callbacks to handle the items it emits and any error or completion notification it issues.
 
 Scheduler:
 
 subscribe does not operate by default on a particular Scheduler.
 
 Parameters:
 
 onSuccess - the Consumer<T> you have designed to accept a success value from the Maybe
 
 onError - the Consumer<Throwable> you have designed to accept any error notification from the Maybe
 
 onComplete - the Action you have designed to accept a completion notification from the Maybe
 
 Returns:
 
 a Disposable reference with which the caller can stop receiving items before the Maybe has finished sending them
 
 Throws:
 
 NullPointerException - if onSuccess is null, or if onError is null, or if onComplete is null
 
 See Also:
 
 ReactiveX operators documentation: Subscribe
 - subscribe
```
@SchedulerSupport(value="none")
public final void subscribe(@NonNull @NonNull MaybeObserver<? super T> observer)
```
 Description copied from interface: MaybeSource
 
 Subscribes the given MaybeObserver to this MaybeSource instance.
 
 Specified by:
 
 subscribe in interface MaybeSource<T>
 
 Parameters:
 
 observer - the MaybeObserver, not null
 - subscribeActual
```
protected abstract void subscribeActual(@NonNull @NonNull MaybeObserver<? super T> observer)
```
 Implement this method in subclasses to handle the incoming MaybeObservers.
 There is no need to call any of the plugin hooks on the current Maybe instance or the MaybeObserver; all hooks and basic safeguards have been applied by subscribe(MaybeObserver) before this method gets called.
 
 Parameters:
 
 observer - the MaybeObserver to handle, not null
 - subscribeOn
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="custom")
public final @NonNull Maybe<T> subscribeOn(@NonNull @NonNull Scheduler scheduler)
```
 Asynchronously subscribes subscribers to this Maybe on the specified Scheduler.
 
 Scheduler:
 
 you specify which Scheduler this operator will use.
 
 Parameters:
 
 scheduler - the Scheduler to perform subscription actions on
 
 Returns:
 
 the new Maybe instance that its subscriptions happen on the specified Scheduler
 
 See Also:
 
 ReactiveX operators documentation: SubscribeOn, RxJava Threading Examples, observeOn(io.reactivex.rxjava3.core.Scheduler)
 - subscribeWith
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final <E extends MaybeObserver<? super T>> E subscribeWith(E observer)
```
 Subscribes a given MaybeObserver (subclass) to this Maybe and returns the given MaybeObserver as is.
 Usage example:
```
 Maybe<Integer> source = Maybe.just(1);
 CompositeDisposable composite = new CompositeDisposable();

 DisposableMaybeObserver<Integer> ds = new DisposableMaybeObserver<>() {
 // ...
 };

 composite.add(source.subscribeWith(ds));
 
```
 Scheduler:
 
 subscribeWith does not operate by default on a particular Scheduler.
 Type Parameters:
 
 E - the type of the MaybeObserver to use and return
 
 Parameters:
 
 observer - the MaybeObserver (subclass) to use and return, not null
 
 Returns:
 
 the input subscriber
 
 Throws:
 
 NullPointerException - if subscriber is null
 - switchIfEmpty
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Maybe<T> switchIfEmpty(@NonNull @NonNull MaybeSource<? extends T> other)
```
 Returns a Maybe that emits the items emitted by the source Maybe or the items of an alternate MaybeSource if the current Maybe is empty.
 
 Scheduler:
 
 switchIfEmpty does not operate by default on a particular Scheduler.
 
 Parameters:
 
 other - the alternate MaybeSource to subscribe to if the main does not emit any items
 
 Returns:
 
 a Maybe that emits the items emitted by the source Maybe or the items of an alternate MaybeSource if the source Maybe is empty.
 - switchIfEmpty
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final @NonNull Single<T> switchIfEmpty(@NonNull @NonNull SingleSource<? extends T> other)
```
 Returns a Single that emits the items emitted by the source Maybe or the item of an alternate SingleSource if the current Maybe is empty.
 
 Scheduler:
 
 switchIfEmpty does not operate by default on a particular Scheduler.
 
 History: 2.1.4 - experimental
 
 Parameters:
 
 other - the alternate SingleSource to subscribe to if the main does not emit any items
 
 Returns:
 
 a Single that emits the items emitted by the source Maybe or the item of an alternate SingleSource if the source Maybe is empty.
 
 Since:
 
 2.2
 - takeUntil
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final  @NonNull Maybe<T> takeUntil(@NonNull @NonNull MaybeSource other)
```
 Returns a Maybe that emits the items emitted by the source Maybe until a second MaybeSource emits an item.
 
 Scheduler:
 
 takeUntil does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 U - the type of items emitted by other
 
 Parameters:
 
 other - the MaybeSource whose first emitted item will cause takeUntil to stop emitting items from the source Maybe
 
 Returns:
 
 a Maybe that emits the items emitted by the source Maybe until such time as other emits its first item
 
 See Also:
 
 ReactiveX operators documentation: TakeUntil
 - takeUntil
```
@BackpressureSupport(value=UNBOUNDED_IN)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final  @NonNull Maybe<T> takeUntil(@NonNull @NonNull Publisher other)
```
 Returns a Maybe that emits the item emitted by the source Maybe until a second Publisher emits an item.
 
 Backpressure:
 
 The Publisher is consumed in an unbounded fashion and is cancelled after the first item emitted.
 
 Scheduler:
 
 takeUntil does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 U - the type of items emitted by other
 
 Parameters:
 
 other - the Publisher whose first emitted item will cause takeUntil to stop emitting items from the source Publisher
 
 Returns:
 
 a Maybe that emits the items emitted by the source Maybe until such time as other emits its first item
 
 See Also:
 
 ReactiveX operators documentation: TakeUntil
 - timeout
```
@CheckReturnValue
 @SchedulerSupport(value="io.reactivex:computation")
 @NonNull
public final @NonNull Maybe<T> timeout(long timeout,
 @NonNull @NonNull TimeUnit timeUnit)
```
 Returns a Maybe that mirrors the source Maybe but applies a timeout policy for each emitted item. If the next item isn't emitted within the specified timeout duration starting from its predecessor, the resulting Maybe terminates and notifies MaybeObservers of a TimeoutException.
 
 Scheduler:
 
 This version of timeout operates by default on the computation Scheduler.
 
 Parameters:
 
 timeout - maximum duration between emitted items before a timeout occurs
 
 timeUnit - the unit of time that applies to the timeout argument.
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: Timeout
 - timeout
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="io.reactivex:computation")
public final @NonNull Maybe<T> timeout(long timeout,
 @NonNull @NonNull TimeUnit timeUnit,
 @NonNull @NonNull MaybeSource<? extends T> fallback)
```
 Returns a Maybe that mirrors the source Maybe but applies a timeout policy for each emitted item. If the next item isn't emitted within the specified timeout duration starting from its predecessor, the source MaybeSource is disposed and resulting Maybe begins instead to mirror a fallback MaybeSource.
 
 Scheduler:
 
 This version of timeout operates by default on the computation Scheduler.
 
 Parameters:
 
 timeout - maximum duration between items before a timeout occurs
 
 timeUnit - the unit of time that applies to the timeout argument
 
 fallback - the fallback MaybeSource to use in case of a timeout
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: Timeout
 - timeout
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="custom")
public final @NonNull Maybe<T> timeout(long timeout,
 @NonNull @NonNull TimeUnit timeUnit,
 @NonNull @NonNull Scheduler scheduler,
 @NonNull @NonNull MaybeSource<? extends T> fallback)
```
 Returns a Maybe that mirrors the source Maybe but applies a timeout policy for each emitted item using a specified Scheduler. If the next item isn't emitted within the specified timeout duration starting from its predecessor, the source MaybeSource is disposed and resulting Maybe begins instead to mirror a fallback MaybeSource.
 
 Scheduler:
 
 You specify which Scheduler this operator will use.
 
 Parameters:
 
 timeout - maximum duration between items before a timeout occurs
 
 timeUnit - the unit of time that applies to the timeout argument
 
 fallback - the MaybeSource to use as the fallback in case of a timeout
 
 scheduler - the Scheduler to run the timeout timers on
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: Timeout
 - timeout
```
@CheckReturnValue
 @SchedulerSupport(value="custom")
 @NonNull
public final @NonNull Maybe<T> timeout(long timeout,
 @NonNull @NonNull TimeUnit timeUnit,
 @NonNull @NonNull Scheduler scheduler)
```
 Returns a Maybe that mirrors the source Maybe but applies a timeout policy for each emitted item, where this policy is governed on a specified Scheduler. If the next item isn't emitted within the specified timeout duration starting from its predecessor, the resulting Maybe terminates and notifies MaybeObservers of a TimeoutException.
 
 Scheduler:
 
 You specify which Scheduler this operator will use.
 
 Parameters:
 
 timeout - maximum duration between items before a timeout occurs
 
 timeUnit - the unit of time that applies to the timeout argument
 
 scheduler - the Scheduler to run the timeout timers on
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: Timeout
 - timeout
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final  @NonNull Maybe<T> timeout(@NonNull @NonNull MaybeSource timeoutIndicator)
```
 If the current Maybe didn't signal an event before the timeoutIndicator MaybeSource signals, a TimeoutException is signaled instead.
 
 Scheduler:
 
 timeout does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 U - the value type of the
 
 Parameters:
 
 timeoutIndicator - the MaybeSource that indicates the timeout by signaling onSuccess or onComplete.
 
 Returns:
 
 the new Maybe instance
 - timeout
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final  @NonNull Maybe<T> timeout(@NonNull @NonNull MaybeSource timeoutIndicator,
 @NonNull @NonNull MaybeSource<? extends T> fallback)
```
 If the current Maybe didn't signal an event before the timeoutIndicator MaybeSource signals, the current Maybe is disposed and the fallback MaybeSource subscribed to as a continuation.
 
 Scheduler:
 
 timeout does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 U - the value type of the
 
 Parameters:
 
 timeoutIndicator - the MaybeSource that indicates the timeout by signaling onSuccess or onComplete.
 
 fallback - the MaybeSource that is subscribed to if the current Maybe times out
 
 Returns:
 
 the new Maybe instance
 - timeout
```
@BackpressureSupport(value=UNBOUNDED_IN)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final  @NonNull Maybe<T> timeout(@NonNull @NonNull Publisher timeoutIndicator)
```
 If the current Maybe source didn't signal an event before the timeoutIndicator Publisher signals, a TimeoutException is signaled instead.
 
 Backpressure:
 
 The timeoutIndicator Publisher is consumed in an unbounded manner and is cancelled after its first item.
 
 Scheduler:
 
 timeout does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 U - the value type of the
 
 Parameters:
 
 timeoutIndicator - the MaybeSource that indicates the timeout by signaling onSuccess or onComplete.
 
 Returns:
 
 the new Maybe instance
 - timeout
```
@BackpressureSupport(value=UNBOUNDED_IN)
 @CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final  @NonNull Maybe<T> timeout(@NonNull @NonNull Publisher timeoutIndicator,
 @NonNull @NonNull MaybeSource<? extends T> fallback)
```
 If the current Maybe didn't signal an event before the timeoutIndicator Publisher signals, the current Maybe is disposed and the fallback MaybeSource subscribed to as a continuation.
 
 Backpressure:
 
 The timeoutIndicator Publisher is consumed in an unbounded manner and is cancelled after its first item.
 
 Scheduler:
 
 timeout does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 U - the value type of the
 
 Parameters:
 
 timeoutIndicator - the MaybeSource that indicates the timeout by signaling onSuccess or onComplete
 
 fallback - the MaybeSource that is subscribed to if the current Maybe times out
 
 Returns:
 
 the new Maybe instance
 - unsubscribeOn
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="custom")
public final @NonNull Maybe<T> unsubscribeOn(@NonNull @NonNull Scheduler scheduler)
```
 Returns a Maybe which makes sure when a MaybeObserver disposes the Disposable, that call is propagated up on the specified scheduler.
 
 Scheduler:
 
 unsubscribeOn calls dispose() of the upstream on the Scheduler you specify.
 
 Parameters:
 
 scheduler - the target scheduler where to execute the disposal
 
 Returns:
 
 the new Maybe instance
 
 Throws:
 
 NullPointerException - if scheduler is null
 - zipWith
```
@CheckReturnValue
 @NonNull
 @SchedulerSupport(value="none")
public final <U,R> @NonNull Maybe<R> zipWith(@NonNull @NonNull MaybeSource<? extends U> other,
 @NonNull @NonNull BiFunction<? super T,? super U,? extends R> zipper)
```
 Waits until this and the other MaybeSource signal a success value then applies the given BiFunction to those values and emits the BiFunction's resulting value to downstream.
 If either this or the other MaybeSource is empty or signals an error, the resulting Maybe will terminate immediately and dispose the other source.
 
 Scheduler:
 
 zipWith does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 U - the type of items emitted by the other MaybeSource
 
 R - the type of items emitted by the resulting Maybe
 
 Parameters:
 
 other - the other MaybeSource
 
 zipper - a function that combines the pairs of items from the two MaybeSources to generate the items to be emitted by the resulting Maybe
 
 Returns:
 
 the new Maybe instance
 
 See Also:
 
 ReactiveX operators documentation: Zip
 - test
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull TestObserver<T> test()
```
 Creates a TestObserver and subscribes it to this Maybe.
 
 Scheduler:
 
 test does not operate by default on a particular Scheduler.
 
 Returns:
 
 the new TestObserver instance
 - test
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull TestObserver<T> test(boolean dispose)
```
 Creates a TestObserver optionally in cancelled state, then subscribes it to this Maybe.
 
 Scheduler:
 
 test does not operate by default on a particular Scheduler.
 
 Parameters:
 
 dispose - if true, the TestObserver will be dispose before subscribing to this Maybe.
 
 Returns:
 
 the new TestObserver instance
 - fromOptional
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public static <T> @NonNull Maybe<T> fromOptional(@NonNull @NonNull Optional<T> optional)
```
 Converts the existing value of the provided optional into a just(Object) or an empty optional into an empty() Maybe instance.
 
 Note that the operator takes an already instantiated optional reference and does not by any means create this original optional. If the optional is to be created per consumer upon subscription, use defer(Supplier) around fromOptional:
```
 Maybe.defer(() -> Maybe.fromOptional(createOptional()));
 
```
 Scheduler:
 
 fromOptional does not operate by default on a particular Scheduler.
 Type Parameters:
 
 T - the element type of the optional value
 
 Parameters:
 
 optional - the optional value to convert into a Maybe
 
 Returns:
 
 the new Maybe instance
 
 Since:
 
 3.0.0
 
 See Also:
 
 just(Object), empty()
 - fromCompletionStage
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public static <T> @NonNull Maybe<T> fromCompletionStage(@NonNull @NonNull CompletionStage<T> stage)
```
 Signals the completion value or error of the given (hot) CompletionStage-based asynchronous calculation.
 
 Note that the operator takes an already instantiated, running or terminated CompletionStage. If the optional is to be created per consumer upon subscription, use defer(Supplier) around fromCompletionStage:
```
 Maybe.defer(() -> Maybe.fromCompletionStage(createCompletionStage()));
 
```
 If the CompletionStage completes with null, the resulting Maybe is completed via onComplete.
 Canceling the flow can't cancel the execution of the CompletionStage because CompletionStage itself doesn't support cancellation. Instead, the operator detaches from the CompletionStage.
 
 Scheduler:
 
 fromCompletionStage does not operate by default on a particular Scheduler.
 Type Parameters:
 
 T - the element type of the CompletionStage
 
 Parameters:
 
 stage - the CompletionStage to convert to Maybe and signal its terminal value or error
 
 Returns:
 
 the new Maybe instance
 
 Since:
 
 3.0.0
 - mapOptional
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final <R> @NonNull Maybe<R> mapOptional(@NonNull @NonNull Function<? super T,Optional<? extends R>> mapper)
```
 Maps the upstream success value into an Optional and emits the contained item if not empty.
 
 Scheduler:
 
 mapOptional does not operate by default on a particular Scheduler.
 
 Type Parameters:
 
 R - the non-null output type
 
 Parameters:
 
 mapper - the function that receives the upstream success item and should return a non-empty Optional to emit as the success output or an empty Optional to complete the Maybe
 
 Returns:
 
 the new Maybe instance
 
 Since:
 
 3.0.0
 
 See Also:
 
 map(Function), filter(Predicate)
 - toCompletionStage
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull CompletionStage<T> toCompletionStage()
```
 Signals the upstream success item (or a NoSuchElementException if the upstream is empty) via a CompletionStage.
 
 The upstream can be canceled by converting the resulting CompletionStage into CompletableFuture via CompletionStage.toCompletableFuture() and calling CompletableFuture.cancel(boolean) on it. The upstream will be also cancelled if the resulting CompletionStage is converted to and completed manually by CompletableFuture.complete(Object) or CompletableFuture.completeExceptionally(Throwable).
 CompletionStages don't have a notion of emptiness and allow nulls, therefore, one can either use toCompletionStage(Object) with null or turn the upstream into a sequence of Optionals and default to Optional.empty():
```
 CompletionStage<Optional<T>> stage = source.map(Optional::of).toCompletionStage(Optional.empty());
 
```
 Scheduler:
 
 toCompletionStage does not operate by default on a particular Scheduler.
 Returns:
 
 the new CompletionStage instance
 
 Since:
 
 3.0.0
 
 See Also:
 
 toCompletionStage(Object)
 - toCompletionStage
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final @NonNull CompletionStage<T> toCompletionStage(@Nullable T defaultItem)
```
 Signals the upstream success item (or the default item if the upstream is empty) via a CompletionStage.
 
 The upstream can be canceled by converting the resulting CompletionStage into CompletableFuture via CompletionStage.toCompletableFuture() and calling CompletableFuture.cancel(boolean) on it. The upstream will be also cancelled if the resulting CompletionStage is converted to and completed manually by CompletableFuture.complete(Object) or CompletableFuture.completeExceptionally(Throwable).
 CompletionStages don't have a notion of emptiness and allow nulls, therefore, one can either use a defaultItem of null or turn the flow into a sequence of Optionals and default to Optional.empty():
```
 CompletionStage<Optional<T>> stage = source.map(Optional::of).toCompletionStage(Optional.empty());
 
```
 Scheduler:
 
 toCompletionStage does not operate by default on a particular Scheduler.
 Parameters:
 
 defaultItem - the item to signal if the upstream is empty
 
 Returns:
 
 the new CompletionStage instance
 
 Since:
 
 3.0.0
 - flattenStreamAsFlowable
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @BackpressureSupport(value=FULL)
 @NonNull
public final <R> @NonNull Flowable<R> flattenStreamAsFlowable(@NonNull @NonNull Function<? super T,? extends Stream<? extends R>> mapper)
```
 Maps the upstream succecss value into a Java Stream and emits its items to the downstream consumer as a Flowable.
 
 The operator closes the Stream upon cancellation and when it terminates. Exceptions raised when closing a Stream are routed to the global error handler (RxJavaPlugins.onError(Throwable). If a Stream should not be closed, turn it into an Iterable and use flattenAsFlowable(Function):
```
 source.flattenAsFlowable(item -> createStream(item)::iterator);
 
```
 Primitive streams are not supported and items have to be boxed manually (e.g., via IntStream.boxed()):
```
 source.flattenStreamAsFlowable(item -> IntStream.rangeClosed(1, 10).boxed());
 
```
 Stream does not support concurrent usage so creating and/or consuming the same instance multiple times from multiple threads can lead to undefined behavior.
 
 Backpressure:
 
 The operator honors backpressure from downstream and iterates the given Stream on demand (i.e., when requested).
 
 Scheduler:
 
 flattenStreamAsFlowable does not operate by default on a particular Scheduler.
 Type Parameters:
 
 R - the element type of the Stream and the output Flowable
 
 Parameters:
 
 mapper - the function that receives the upstream success item and should return a Stream of values to emit.
 
 Returns:
 
 the new Flowable instance
 
 Since:
 
 3.0.0
 
 See Also:
 
 flattenAsFlowable(Function), flattenStreamAsObservable(Function)
 - flattenStreamAsObservable
```
@CheckReturnValue
 @SchedulerSupport(value="none")
 @NonNull
public final <R> @NonNull Observable<R> flattenStreamAsObservable(@NonNull @NonNull Function<? super T,? extends Stream<? extends R>> mapper)
```
 Maps the upstream succecss value into a Java Stream and emits its items to the downstream consumer as an Observable.
 The operator closes the Stream upon cancellation and when it terminates. Exceptions raised when closing a Stream are routed to the global error handler (RxJavaPlugins.onError(Throwable). If a Stream should not be closed, turn it into an Iterable and use flattenAsObservable(Function):
```
 source.flattenAsObservable(item -> createStream(item)::iterator);
 
```
 Primitive streams are not supported and items have to be boxed manually (e.g., via IntStream.boxed()):
```
 source.flattenStreamAsObservable(item -> IntStream.rangeClosed(1, 10).boxed());
 
```
 Stream does not support concurrent usage so creating and/or consuming the same instance multiple times from multiple threads can lead to undefined behavior.
 
 Scheduler:
 
 flattenStreamAsObservable does not operate by default on a particular Scheduler.
 Type Parameters:
 
 R - the element type of the Stream and the output Observable
 
 Parameters:
 
 mapper - the function that receives the upstream success item and should return a Stream of values to emit.
 
 Returns:
 
 the new Observable instance
 
 Since:
 
 3.0.0
 
 See Also:
 
 flattenAsObservable(Function), flattenStreamAsFlowable(Function)