The `FluxMessageChannel.destroy()` may fail with `Spec. Rule 1.3`

[artembilan]

Due to race condition between this.sink.tryEmitNext() and this.sink.emitComplete(), there could be a situation when onNext signal slips after onComplete. Appears on fast producers into this FluxMessageChannel.

The error in logs looks like:

2025-02-26 17:39:51,315 WARN [main] [org.springframework.beans.factory.support.DisposableBeanAdapter] - Invocation of destroy method failed on bean with name 'org.springframework.integration.channel.FluxMessageChannel'
reactor.core.publisher.Sinks$EmissionException: Spec. Rule 1.3 - onSubscribe, onNext, onError and onComplete signaled to a Subscriber MUST be signaled serially.
	at reactor.core.publisher.InternalManySink.emitComplete(InternalManySink.java:86) ~[reactor-core-3.7.3.jar:3.7.3]
	at org.springframework.integration.channel.FluxMessageChannel.destroy(FluxMessageChannel.java:174) ~[classes/:?]
	at org.springframework.beans.factory.support.DisposableBeanAdapter.destroy(DisposableBeanAdapter.java:211) ~[spring-beans-6.2.3.jar:6.2.3]

Right, the DisposableBeanAdapter hides an exception behind the warn message, but calling FluxMessageChannel.destroy() may lead to failures in the target application.
For example, when beans are destroyed manually, not via BeanFactory.