T - the input and output value typeSinks through
 variations of Sinks.many().multicast().onBackpressureBuffer().
 If you really need the subscribe-to-upstream functionality of a Processor, switch
 to Sinks.ManyWithUpstream with Sinks.unsafe() variants of Sinks.unsafe().manyWithUpstream().
 This processor was blocking in onNext(Object). This behaviour can be implemented with the Sinks API by calling
 Sinks.Many.tryEmitNext(Object) and retrying, e.g.:
  while (sink.tryEmitNext(v).hasFailed()) {
     LockSupport.parkNanos(10);
 }
 @Deprecated public final class EmitterProcessor<T> extends FluxProcessor<T,T> implements Sinks.ManyWithUpstream<T>
 The default create() factories will only produce the new elements observed in
 the parent sequence after a given Subscriber is subscribed.
 
  
 
Scannable.Attr<T>Disposable.Composite, Disposable.SwapOPERATOR_NAME_UNRELATED_WORDS_PATTERN| Modifier and Type | Method and Description | 
|---|---|
| Flux<T> | asFlux()Deprecated.  Return a  Fluxview of this sink. | 
| static <E> EmitterProcessor<E> | create()Deprecated. 
 use  Sinks.many().multicast().onBackpressureBuffer()(or the unsafe variant if you're sure about external synchronization). To be removed in 3.5. | 
| static <E> EmitterProcessor<E> | create(boolean autoCancel)Deprecated. 
 use  Sinks.many().multicast().onBackpressureBuffer(bufferSize, boolean)using the old default ofQueues.SMALL_BUFFER_SIZEfor thebufferSize(or the unsafe variant if you're sure about external synchronization). To be removed in 3.5. | 
| static <E> EmitterProcessor<E> | create(int bufferSize)Deprecated. 
 use  Sinks.many().multicast().onBackpressureBuffer(bufferSize)(or the unsafe variant if you're sure about external synchronization). To be removed in 3.5. | 
| static <E> EmitterProcessor<E> | create(int bufferSize,
      boolean autoCancel)Deprecated. 
 use  Sinks.many().multicast().onBackpressureBuffer(bufferSize, autoCancel)(or the unsafe variant if you're sure about external synchronization). To be removed in 3.5. | 
| Context | currentContext()Deprecated.  Request a  Contextfrom dependent components which can include downstream
 operators during subscribing or a terminalSubscriber. | 
| int | currentSubscriberCount()Deprecated.  Get how many  Subscribersare currently subscribed to the sink. | 
| long | downstreamCount()Deprecated.  Return the number of active  Subscriberor -1 if untracked. | 
| default void | emitComplete(Sinks.EmitFailureHandler failureHandler)A simplified attempt at completing via the  Sinks.Many.tryEmitComplete()API, generating anonCompletesignal. | 
| default void | emitError(Throwable error,
         Sinks.EmitFailureHandler failureHandler)A simplified attempt at failing the sequence via the  Sinks.Many.tryEmitError(Throwable)API, generating anonErrorsignal. | 
| default void | emitNext(T value,
        Sinks.EmitFailureHandler failureHandler)A simplified attempt at emitting a non-null element via the  Sinks.Many.tryEmitNext(Object)API, generating anonNextsignal. | 
| int | getBufferSize()Deprecated.  Return the processor buffer capacity if any or  Integer.MAX_VALUE | 
| Throwable | getError()Deprecated.  Current error if any, default to null | 
| int | getPending()Deprecated.  Return the number of parked elements in the emitter backlog. | 
| int | getPrefetch()Deprecated.  The prefetch configuration of the  Flux | 
| Stream<? extends Scannable> | inners()Deprecated.  Return a  Streamof referenced inners (flatmap, multicast etc) | 
| boolean | isCancelled()Deprecated.  | 
| boolean | isDisposed()Deprecated.  Optionally return true when the resource or task is disposed. | 
| protected boolean | isIdentityProcessor()Deprecated.  Return true if  FluxProcessor<T, T> | 
| boolean | isTerminated()Deprecated.  Has this upstream finished or "completed" / "failed" ? | 
| void | onComplete()Deprecated.  | 
| void | onError(Throwable throwable)Deprecated.  | 
| void | onNext(T t)Deprecated.  | 
| void | onSubscribe(Subscription s)Deprecated.  Implementors should initialize any state used by  Subscriber.onNext(Object)before
 callingSubscription.request(long). | 
| Object | scanUnsafe(Scannable.Attr key)Deprecated.  This method is used internally by components to define their key-value mappings
 in a single place. | 
| void | subscribe(CoreSubscriber<? super T> actual)Deprecated.  An internal  Publisher.subscribe(Subscriber)that will bypassHooks.onLastOperator(Function)pointcut. | 
| Disposable | subscribeTo(Publisher<? extends T> upstream)Deprecated.  Explicitly subscribe this  Sinks.Manyto an upstreamPublisherwithout
 exposing it as aSubscriberat all. | 
| Sinks.EmitResult | tryEmitComplete()Deprecated.  Try to terminate the sequence successfully, generating an  onCompletesignal. | 
| Sinks.EmitResult | tryEmitError(Throwable t)Deprecated.  Try to fail the sequence, generating an  onErrorsignal. | 
| Sinks.EmitResult | tryEmitNext(T t)Deprecated.  Try emitting a non-null element, generating an  onNextsignal. | 
dispose, hasCompleted, hasDownstreams, hasError, isSerialized, serialize, serializeAlways, sink, sink, switchOnNext, wrapall, any, as, blockFirst, blockFirst, blockLast, blockLast, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, buffer, bufferTimeout, bufferTimeout, bufferTimeout, bufferTimeout, bufferTimeout, bufferTimeout, bufferTimeout, bufferTimeout, bufferUntil, bufferUntil, bufferUntilChanged, bufferUntilChanged, bufferUntilChanged, bufferWhen, bufferWhen, bufferWhile, cache, cache, cache, cache, cache, cache, cancelOn, cast, checkpoint, checkpoint, checkpoint, collect, collect, collectList, collectMap, collectMap, collectMap, collectMultimap, collectMultimap, collectMultimap, collectSortedList, collectSortedList, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, combineLatest, concat, concat, concat, concat, concatDelayError, concatDelayError, concatDelayError, concatDelayError, concatMap, concatMap, concatMapDelayError, concatMapDelayError, concatMapDelayError, concatMapIterable, concatMapIterable, concatWith, concatWithValues, contextCapture, contextWrite, contextWrite, count, create, create, defaultIfEmpty, defer, deferContextual, delayElements, delayElements, delaySequence, delaySequence, delaySubscription, delaySubscription, delaySubscription, delayUntil, dematerialize, distinct, distinct, distinct, distinct, distinctUntilChanged, distinctUntilChanged, distinctUntilChanged, doAfterTerminate, doFinally, doFirst, doOnCancel, doOnComplete, doOnDiscard, doOnEach, doOnError, doOnError, doOnError, doOnNext, doOnRequest, doOnSubscribe, doOnTerminate, elapsed, elapsed, elementAt, elementAt, empty, error, error, error, expand, expand, expandDeep, expandDeep, filter, filterWhen, filterWhen, first, first, firstWithSignal, firstWithSignal, firstWithValue, firstWithValue, flatMap, flatMap, flatMap, flatMap, flatMapDelayError, flatMapIterable, flatMapIterable, flatMapSequential, flatMapSequential, flatMapSequential, flatMapSequentialDelayError, from, fromArray, fromIterable, fromStream, fromStream, generate, generate, generate, groupBy, groupBy, groupBy, groupBy, groupJoin, handle, hasElement, hasElements, hide, ignoreElements, index, index, interval, interval, interval, interval, join, just, just, last, last, limitRate, limitRate, limitRequest, log, log, log, log, log, log, map, mapNotNull, materialize, merge, merge, merge, merge, merge, merge, mergeComparing, mergeComparing, mergeComparing, mergeComparingDelayError, mergeComparingWith, mergeDelayError, mergeOrdered, mergeOrdered, mergeOrdered, mergeOrderedWith, mergePriority, mergePriority, mergePriority, mergePriorityDelayError, mergeSequential, mergeSequential, mergeSequential, mergeSequential, mergeSequential, mergeSequential, mergeSequentialDelayError, mergeSequentialDelayError, mergeSequentialDelayError, mergeWith, metrics, name, never, next, ofType, onAssembly, onAssembly, onBackpressureBuffer, onBackpressureBuffer, onBackpressureBuffer, onBackpressureBuffer, onBackpressureBuffer, onBackpressureBuffer, onBackpressureBuffer, onBackpressureDrop, onBackpressureDrop, onBackpressureError, onBackpressureLatest, onErrorComplete, onErrorComplete, onErrorComplete, onErrorContinue, onErrorContinue, onErrorContinue, onErrorMap, onErrorMap, onErrorMap, onErrorResume, onErrorResume, onErrorResume, onErrorReturn, onErrorReturn, onErrorReturn, onErrorStop, onTerminateDetach, or, parallel, parallel, parallel, publish, publish, publish, publish, publishNext, publishOn, publishOn, publishOn, push, push, range, reduce, reduce, reduceWith, repeat, repeat, repeat, repeat, repeatWhen, replay, replay, replay, replay, replay, replay, retry, retry, retryWhen, sample, sample, sampleFirst, sampleFirst, sampleTimeout, sampleTimeout, scan, scan, scanWith, share, shareNext, single, single, singleOrEmpty, skip, skip, skip, skipLast, skipUntil, skipUntilOther, skipWhile, sort, sort, startWith, startWith, startWith, subscribe, subscribe, subscribe, subscribe, subscribe, subscribe, subscribe, subscribeOn, subscribeOn, subscribeWith, switchIfEmpty, switchMap, switchMap, switchOnFirst, switchOnFirst, switchOnNext, switchOnNext, tag, take, take, take, take, takeLast, takeUntil, takeUntilOther, takeWhile, tap, tap, tap, then, then, thenEmpty, thenMany, timed, timed, timeout, timeout, timeout, timeout, timeout, timeout, timeout, timestamp, timestamp, toIterable, toIterable, toIterable, toStream, toStream, toString, transform, transformDeferred, transformDeferredContextual, using, using, using, using, usingWhen, usingWhen, window, window, window, window, window, window, window, windowTimeout, windowTimeout, windowTimeout, windowTimeout, windowUntil, windowUntil, windowUntil, windowUntilChanged, windowUntilChanged, windowUntilChanged, windowWhen, windowWhile, windowWhile, withLatestFrom, zip, zip, zip, zip, zip, zip, zip, zip, zip, zip, zip, zip, zip, zipWith, zipWith, zipWith, zipWith, zipWithIterable, zipWithIterableclone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitactuals, from, isScanAvailable, name, parents, scan, scanOrDefault, stepName, steps, tags, tagsDeduplicated@Deprecated public static <E> EmitterProcessor<E> create()
Sinks.many().multicast().onBackpressureBuffer()
 (or the unsafe variant if you're sure about external synchronization). To be removed in 3.5.EmitterProcessor using Queues.SMALL_BUFFER_SIZE
 backlog size and auto-cancel.E - Type of processed signals@Deprecated public static <E> EmitterProcessor<E> create(boolean autoCancel)
Sinks.many().multicast().onBackpressureBuffer(bufferSize, boolean)
 using the old default of Queues.SMALL_BUFFER_SIZE for the bufferSize
 (or the unsafe variant if you're sure about external synchronization). To be removed in 3.5.EmitterProcessor using Queues.SMALL_BUFFER_SIZE
 backlog size and the provided auto-cancel.E - Type of processed signalsautoCancel - automatically cancel@Deprecated public static <E> EmitterProcessor<E> create(int bufferSize)
Sinks.many().multicast().onBackpressureBuffer(bufferSize)
 (or the unsafe variant if you're sure about external synchronization). To be removed in 3.5.EmitterProcessor using the provided backlog size, with auto-cancel.E - Type of processed signalsbufferSize - the internal buffer size to hold signals@Deprecated public static <E> EmitterProcessor<E> create(int bufferSize, boolean autoCancel)
Sinks.many().multicast().onBackpressureBuffer(bufferSize, autoCancel)
 (or the unsafe variant if you're sure about external synchronization). To be removed in 3.5.EmitterProcessor using the provided backlog size and auto-cancellation.E - Type of processed signalsbufferSize - the internal buffer size to hold signalsautoCancel - automatically cancelpublic Stream<? extends Scannable> inners()
ScannableStream of referenced inners (flatmap, multicast etc)public Context currentContext()
CoreSubscriberContext from dependent components which can include downstream
 operators during subscribing or a terminal Subscriber.currentContext in interface CoreSubscriber<T>currentContext in class FluxProcessor<T,T>Context.empty()public Disposable subscribeTo(Publisher<? extends T> upstream)
Sinks.ManyWithUpstreamSinks.Many to an upstream Publisher without
 exposing it as a Subscriber at all.
 
 Note that when this is done, one MUST stop using emit/tryEmit APIs, reserving signal
 creation to be the sole responsibility of the upstream Publisher.
 
 The returned Disposable provides a way of both unsubscribing from the upstream
 and terminating the sink: currently registered subscribers downstream receive an onError
 signal with a CancellationException and further attempts at subscribing
 to the sink will trigger a similar signal immediately (in which case the returned Disposable might be no-op).
 
 Any attempt at subscribing the same Sinks.ManyWithUpstream multiple times throws an IllegalStateException
 indicating that the subscription must be unique.
subscribeTo in interface Sinks.ManyWithUpstream<T>public void subscribe(CoreSubscriber<? super T> actual)
FluxPublisher.subscribe(Subscriber) that will bypass
 Hooks.onLastOperator(Function) pointcut.
 
 In addition to behave as expected by Publisher.subscribe(Subscriber)
 in a controlled manner, it supports direct subscribe-time Context passing.
subscribe in interface CorePublisher<T>subscribe in class Flux<T>actual - the Subscriber interested into the published sequenceFlux.subscribe(Subscriber)public void onComplete()
onComplete in interface Subscriber<T>public Sinks.EmitResult tryEmitComplete()
Sinks.ManyonComplete
 signal. The result of the attempt is represented as an Sinks.EmitResult, which possibly indicates error cases.
 
 See the list of failure Sinks.EmitResult in #emitComplete(EmitFailureHandler) javadoc for an
 example of how each of these can be dealt with, to decide if the emit API would be a good enough fit instead.
tryEmitComplete in interface Sinks.Many<T>Sinks.EmitResult, which should be checked to distinguish different possible failuresSubscriber.onComplete()public void onError(Throwable throwable)
onError in interface Subscriber<T>public Sinks.EmitResult tryEmitError(Throwable t)
Sinks.ManyonError
 signal. The result of the attempt is represented as an Sinks.EmitResult, which possibly indicates error cases.
 
 See the list of failure Sinks.EmitResult in #emitError(Throwable, EmitFailureHandler) javadoc for an
 example of how each of these can be dealt with, to decide if the emit API would be a good enough fit instead.
tryEmitError in interface Sinks.Many<T>t - the exception to signal, not nullSinks.EmitResult, which should be checked to distinguish different possible failuresSubscriber.onError(Throwable)public void onNext(T t)
onNext in interface Subscriber<T>public Sinks.EmitResult tryEmitNext(T t)
Sinks.ManyonNext signal.
 The result of the attempt is represented as an Sinks.EmitResult, which possibly indicates error cases.
 
 See the list of failure Sinks.EmitResult in #emitNext(Object, EmitFailureHandler) javadoc for an
 example of how each of these can be dealt with, to decide if the emit API would be a good enough fit instead.
 
Might throw an unchecked exception as a last resort (eg. in case of a fatal error downstream which cannot be propagated to any asynchronous handler, a bubbling exception, ...).
tryEmitNext in interface Sinks.Many<T>t - the value to emit, not nullSinks.EmitResult, which should be checked to distinguish different possible failuresSubscriber.onNext(Object)public int currentSubscriberCount()
Sinks.ManySubscribers are currently subscribed to the sink.
 
 This is a best effort peek at the sink state, and a subsequent attempt at emitting
 to the sink might still return Sinks.EmitResult.FAIL_ZERO_SUBSCRIBER where relevant.
 (generally in Sinks.Many.tryEmitNext(Object)). Request (and lack thereof) isn't taken
 into account, all registered subscribers are counted.
currentSubscriberCount in interface Sinks.Many<T>public Flux<T> asFlux()
Sinks.ManyFlux view of this sink. Every call returns the same instance.asFlux in interface Sinks.Many<T>Flux view associated to this Sinks.Manyprotected boolean isIdentityProcessor()
FluxProcessorFluxProcessor<T, T>isIdentityProcessor in class FluxProcessor<T,T>FluxProcessor<T, T>public int getPending()
public boolean isDisposed()
DisposableImplementations are not required to track disposition and as such may never return true even when disposed. However, they MUST only return true when there's a guarantee the resource or task is disposed.
isDisposed in interface Disposablepublic void onSubscribe(Subscription s)
CoreSubscriberSubscriber.onNext(Object) before
 calling Subscription.request(long). Should further onNext related
 state modification occur, thread-safety will be required.
 
    Note that an invalid request <= 0 will not produce an onError and
    will simply be ignored or reported through a debug-enabled
    Logger.
 
onSubscribe in interface Subscriber<T>onSubscribe in interface CoreSubscriber<T>@Nullable public Throwable getError()
FluxProcessorgetError in class FluxProcessor<T,T>public boolean isCancelled()
public final int getBufferSize()
FluxProcessorInteger.MAX_VALUEgetBufferSize in class FluxProcessor<T,T>Integer.MAX_VALUEpublic boolean isTerminated()
FluxProcessorisTerminated in class FluxProcessor<T,T>public int getPrefetch()
FluxFluxgetPrefetch in class Flux<T>Flux, -1 if unspecified@Nullable public Object scanUnsafe(Scannable.Attr key)
ScannableScannable.Attr key,
 implementors should take care to return values of the correct type, and return
 null if no specific value is available.
 
 For public consumption of attributes, prefer using Scannable.scan(Attr), which will
 return a typed value and fall back to the key's default if the component didn't
 define any mapping.
scanUnsafe in interface ScannablescanUnsafe in class FluxProcessor<T,T>key - a Scannable.Attr to resolve for the component.public long downstreamCount()
FluxProcessorSubscriber or -1 if untracked.downstreamCount in class FluxProcessor<T,T>Subscriber or -1 if untrackedpublic void emitNext(T value,
                     Sinks.EmitFailureHandler failureHandler)
Sinks.ManySinks.Many.tryEmitNext(Object) API, generating an
 onNext signal.
 If the result of the attempt is not a success, implementations SHOULD retry the
 Sinks.Many.tryEmitNext(Object) call IF the provided Sinks.EmitFailureHandler returns true.
 Otherwise, failures are dealt with in a predefined way that might depend on the actual sink implementation
 (see below for the vanilla reactor-core behavior).
 
 Generally, Sinks.Many.tryEmitNext(Object) is preferable since it allows a custom handling
 of error cases, although this implies checking the returned Sinks.EmitResult and correctly
 acting on it. This API is intended as a good default for convenience.
 
 When the Sinks.EmitResult is not a success, vanilla reactor-core operators have the following behavior:
 
Sinks.EmitResult.FAIL_ZERO_SUBSCRIBER: no particular handling. should ideally discard the value but at that
         point there's no Subscriber from which to get a contextual discard handler.
     Sinks.EmitResult.FAIL_OVERFLOW: discard the value (Operators.onDiscard(Object, Context))
         then call Sinks.Many.emitError(Throwable, Sinks.EmitFailureHandler) with a Exceptions.failWithOverflow(String) exception.
     Sinks.EmitResult.FAIL_CANCELLED: discard the value (Operators.onDiscard(Object, Context)).
     Sinks.EmitResult.FAIL_TERMINATED: drop the value (Operators.onNextDropped(Object, Context)).
     Sinks.EmitResult.FAIL_NON_SERIALIZED: throw an Sinks.EmissionException mentioning RS spec rule 1.3.
         Note that Sinks.unsafe() never trigger this result. It would be possible for an Sinks.EmitFailureHandler
         to busy-loop and optimistically wait for the contention to disappear to avoid this case for safe sinks...
     
 Might throw an unchecked exception as a last resort (eg. in case of a fatal error downstream which cannot
 be propagated to any asynchronous handler, a bubbling exception, a Sinks.EmitResult.FAIL_NON_SERIALIZED
 as described above, ...).
emitNext in interface Sinks.Many<T>value - the value to emit, not nullfailureHandler - the failure handler that allows retrying failed Sinks.EmitResult.Sinks.Many.tryEmitNext(Object), 
Subscriber.onNext(Object)public void emitComplete(Sinks.EmitFailureHandler failureHandler)
Sinks.ManySinks.Many.tryEmitComplete() API, generating an
 onComplete signal.
 If the result of the attempt is not a success, implementations SHOULD retry the
 Sinks.Many.tryEmitComplete() call IF the provided Sinks.EmitFailureHandler returns true.
 Otherwise, failures are dealt with in a predefined way that might depend on the actual sink implementation
 (see below for the vanilla reactor-core behavior).
 
 Generally, Sinks.Many.tryEmitComplete() is preferable since it allows a custom handling
 of error cases, although this implies checking the returned Sinks.EmitResult and correctly
 acting on it. This API is intended as a good default for convenience.
 
 When the Sinks.EmitResult is not a success, vanilla reactor-core operators have the following behavior:
 
Sinks.EmitResult.FAIL_OVERFLOW: irrelevant as onComplete is not driven by backpressure.
     Sinks.EmitResult.FAIL_ZERO_SUBSCRIBER: the completion can be ignored since nobody is listening.
         Note that most vanilla reactor sinks never trigger this result for onComplete, replaying the
         terminal signal to later subscribers instead (to the exception of Sinks.UnicastSpec.onBackpressureError()).
     Sinks.EmitResult.FAIL_CANCELLED: the completion can be ignored since nobody is interested.
     Sinks.EmitResult.FAIL_TERMINATED: the extra completion is basically ignored since there was a previous
         termination signal, but there is nothing interesting to log.
     Sinks.EmitResult.FAIL_NON_SERIALIZED: throw an Sinks.EmissionException mentioning RS spec rule 1.3.
         Note that Sinks.unsafe() never trigger this result. It would be possible for an Sinks.EmitFailureHandler
         to busy-loop and optimistically wait for the contention to disappear to avoid this case in safe sinks...
     
 Might throw an unchecked exception as a last resort (eg. in case of a fatal error downstream which cannot
 be propagated to any asynchronous handler, a bubbling exception, a Sinks.EmitResult.FAIL_NON_SERIALIZED
 as described above, ...).
emitComplete in interface Sinks.Many<T>failureHandler - the failure handler that allows retrying failed Sinks.EmitResult.Sinks.Many.tryEmitComplete(), 
Subscriber.onComplete()public void emitError(Throwable error, Sinks.EmitFailureHandler failureHandler)
Sinks.ManySinks.Many.tryEmitError(Throwable) API, generating an
 onError signal.
 If the result of the attempt is not a success, implementations SHOULD retry the
 Sinks.Many.tryEmitError(Throwable) call IF the provided Sinks.EmitFailureHandler returns true.
 Otherwise, failures are dealt with in a predefined way that might depend on the actual sink implementation
 (see below for the vanilla reactor-core behavior).
 
 Generally, Sinks.Many.tryEmitError(Throwable) is preferable since it allows a custom handling
 of error cases, although this implies checking the returned Sinks.EmitResult and correctly
 acting on it. This API is intended as a good default for convenience.
 
 When the Sinks.EmitResult is not a success, vanilla reactor-core operators have the following behavior:
 
Sinks.EmitResult.FAIL_OVERFLOW: irrelevant as onError is not driven by backpressure.
     Sinks.EmitResult.FAIL_ZERO_SUBSCRIBER: the error is ignored since nobody is listening. Note that most vanilla reactor sinks
         never trigger this result for onError, replaying the terminal signal to later subscribers instead
         (to the exception of Sinks.UnicastSpec.onBackpressureError()).
     Sinks.EmitResult.FAIL_CANCELLED: the error can be ignored since nobody is interested.
      Sinks.EmitResult.FAIL_TERMINATED: the error unexpectedly follows another terminal signal, so it is
         dropped via Operators.onErrorDropped(Throwable, Context).
     Sinks.EmitResult.FAIL_NON_SERIALIZED: throw an Sinks.EmissionException mentioning RS spec rule 1.3.
         Note that Sinks.unsafe() never trigger this result. It would be possible for an Sinks.EmitFailureHandler
         to busy-loop and optimistically wait for the contention to disappear to avoid this case in safe sinks...
     
 Might throw an unchecked exception as a last resort (eg. in case of a fatal error downstream which cannot
 be propagated to any asynchronous handler, a bubbling exception, a Sinks.EmitResult.FAIL_NON_SERIALIZED
 as described above, ...).
emitError in interface Sinks.Many<T>error - the exception to signal, not nullfailureHandler - the failure handler that allows retrying failed Sinks.EmitResult.Sinks.Many.tryEmitError(Throwable), 
Subscriber.onError(Throwable)