FluxPublish does not propagate subscriber context

[andreisilviudragnea]

Expected Behavior

FluxPublish should propagate the first subscriber context, as, for example, FluxReplay does, after #1114 got fixed.

Actual Behavior

FluxPublish does not propagate any subscriber context.

Steps to Reproduce

@Test
public void subscriberContextPropagation() {
	String key = "key";
	int expectedValue = 1;
	Flux<Integer> integerFlux =
			Flux.just(1, 2, 3)
			    .flatMap(value ->
					    Mono.subscriberContext()
					        .doOnNext(context -> assertThat((int) conte
							        .isEqualTo(expectedValue)
					        )
					        .thenReturn(value)
			    )
			    .publish()
			    .autoConnect(2);
	integerFlux.subscriberContext(Context.of(key, expectedValue))
	           .subscribe();
	integerFlux.subscriberContext(Context.of(key, 2))
	           .subscribe();
}

Possible Solution

Override CoreSubscriber.currentContext() in FluxPublish.PublishSubscriber:

@Override
public Context currentContext() {
	return Operators.multiSubscribersContext(subscribers);
}

Your Environment

• Reactor version(s) used: 3.3.0.RELEASE
• Other relevant libraries versions (eg. netty, ...):
• JVM version (javar -version):

openjdk version "1.8.0_232"
OpenJDK Runtime Environment (Zulu 8.42.0.21-CA-macosx) (build 1.8.0_232-b18)
OpenJDK 64-Bit Server VM (Zulu 8.42.0.21-CA-macosx) (build 25.232-b18, mixed mode)

• OS and version (eg uname -a):

Darwin 192-168-0-196.rdsnet.ro 19.0.0 Darwin Kernel Version 19.0.0: Thu Oct 17 16:17:15 PDT 2019; root:xnu-6153.41.3~29/RELEASE_X86_64 x86_64