Annotating endpoints returning Flowable<> type with @ContinueSpan in case of any exception always throws ClassCastException

[Roodek]

Expected Behavior

throwing expected exception 400 - Bad request

Actual Behaviour

adding @ContinueSpan annotation prevents the propagation of expected exception
throwing 500-internal Server Error instead

the thrown exception is
Unexpected error occurred: class io.micronaut.core.async.publisher.Publishers$JustThrowPublisher cannot be cast to class io.reactivex.Flowable (io.micronaut.core.async.publisher.Publishers$JustThrowPublisher and io.reactivex.Flowable are in unnamed module of loader 'app') java.lang.ClassCastException: class io.micronaut.core.async.publisher.Publishers$JustThrowPublisher cannot be cast to class io.reactivex.Flowable (io.micronaut.core.async.publisher.Publishers$JustThrowPublisher and io.reactivex.Flowable are in unnamed module of loader 'app')

is there a way to trace endpoints returning Flowable ?

Steps To Reproduce

• Clone micronaut "Hello world" example project
• Add endpoint returning Flowable<> type

@Controller("/hello") 
public class HelloController {
    @Get 
    @Produces(MediaType.TEXT_PLAIN) 
    public String index() {
        return "Hello World";
    }


    @Get("/err") 
    @ContinueSpan
    public Flowable<String> flowable() {
        try{
            throwException();
        }catch (Exception e){
            return Flowable.error(e);
        }
        return Flowable.just("example value");
    }

    private void throwException(){
        throw new HttpStatusException(HttpStatus.BAD_REQUEST,"wrong isolation");

    }
}

• Call endpoint "/err"

Environment Information

JDK 11

Example Application

No response

Version

2.5.13, 3.6.3

[kalmar]

Have similar issue in my reactive app -- my async service annotated with @ContinueSpan just fails with:

java.lang.ClassCastException: class io.micronaut.core.async.publisher.Publishers$JustThrowPublisher cannot be cast to class reactor.core.publisher.Mono (io.micronaut.core.async.publisher.Publishers$JustThrowPublisher and reactor.core.publisher.Mono are in unnamed module of loader 'app')
	at ru.tinkoff.dwh.hercule.we.executor.$WorkspaceExecutorImpl$Definition$Intercepted.execute(Unknown Source)

Pls help!