Reproducer sample for Reactor 3.6+ and TracingLifter issue (ClassCastException)

This sample is created to demonstrate an issue that was found on SpringBoot 3.2+ reactive application and Couchbase java client 3.4.11. The issue is triggered by a get request to couchbase server. The sample is based on code from couchbase-jvm-client repo

To trigger the issue the following conditions must be fulfilled:

• Hooks.enableAutomaticContextPropagation() must be called
• a micrometer jar should be in class path
• onEachOperator hook is set up and provided a function that sets up tracing lift operator.
• a reactor-core 3.6+

Starting the sample:

• Run ReactorClassCastExceptionReproducerSample.main(String[] args)

Expected behaviour

• Sample throws no exception

Actual behaviour

• java.lang.ClassCastException exception is thrown class reactor.core.publisher.FluxContextWriteRestoringThreadLocals$ContextWriteRestoringThreadLocalsSubscriber cannot be cast to class reactor.core.Fuseable$QueueSubscription

Notes

• Calling Hooks.onOperatorDebug() "fixes" the problem, since lift is wrapped in another object.