Spring Security Make EnableReactiveMethodSecurity compatible with Kotlin Coroutines

Current implementation of PrePostAdviceReactiveMethodInterceptor makes it impossible to use @Pre/PostAuthorize with suspending functions:

// PrePostAdviceReactiveMethodInterceptor::invoke
if (!Publisher.class.isAssignableFrom(returnType)) {
    throw new IllegalStateException("The returnType " + returnType + " on " + method + " must return an instance of org.reactivestreams.Publisher (i.e. Mono / Flux) in order to support Reactor Context");
}

This may be related to spring-projects/spring-framework#22462

Spring boot version: 2.2.1.RELEASE

Comment From: rwinch

Could you please provide a complete sample?

Comment From: TonCherAmi

@rwinch here you go.

Upon making a request,

curl -X POST -v -u admin:qwerty localhost:8080/api/test -d "xzcvxzcv"

an exception is thrown:

{
  "timestamp": "2020-03-18T19:57:41.277+0000",
  "path": "/api/test",
  "status": 500,
  "error": "Internal Server Error",
  "message": "The returnType class java.lang.Object on public java.lang.Object com.example.demo.handlers.TestHandler.test(org.springframework.web.reactive.function.server.ServerRequest,kotlin.coroutines.Continuation) must return an instance of org.reactivestreams.Publisher (i.e. Mono / Flux) in order to support Reactor Context",
  "requestId": "38010f7a-4"
}

Complete stacktrace:

2020-03-18 23:01:43.416 ERROR 5208 --- [oundedElastic-1] a.w.r.e.AbstractErrorWebExceptionHandler : [c3f2d0af-1]  500 Server Error for HTTP POST "/api/test"

java.lang.IllegalStateException: The returnType class java.lang.Object on public java.lang.Object com.example.demo.handlers.TestHandler.test(org.springframework.web.reactive.function.server.ServerRequest,kotlin.coroutines.Continuation) must return an instance of org.reactivestreams.Publisher (i.e. Mono / Flux) in order to support Reactor Context
    at org.springframework.security.access.prepost.PrePostAdviceReactiveMethodInterceptor.invoke(PrePostAdviceReactiveMethodInterceptor.java:76) ~[spring-security-core-5.3.0.RELEASE.jar:5.3.0.RELEASE]
    Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
    |_ checkpoint ⇢ org.springframework.security.web.server.authorization.AuthorizationWebFilter [DefaultWebFilterChain]
    |_ checkpoint ⇢ org.springframework.security.web.server.authorization.ExceptionTranslationWebFilter [DefaultWebFilterChain]
    |_ checkpoint ⇢ org.springframework.security.web.server.authentication.logout.LogoutWebFilter [DefaultWebFilterChain]
    |_ checkpoint ⇢ org.springframework.security.web.server.savedrequest.ServerRequestCacheWebFilter [DefaultWebFilterChain]
    |_ checkpoint ⇢ org.springframework.security.web.server.context.SecurityContextServerWebExchangeWebFilter [DefaultWebFilterChain]
    |_ checkpoint ⇢ org.springframework.security.web.server.authentication.AuthenticationWebFilter [DefaultWebFilterChain]
    |_ checkpoint ⇢ org.springframework.security.web.server.context.ReactorContextWebFilter [DefaultWebFilterChain]
    |_ checkpoint ⇢ org.springframework.security.web.server.header.HttpHeaderWriterWebFilter [DefaultWebFilterChain]
    |_ checkpoint ⇢ org.springframework.security.config.web.server.ServerHttpSecurity$ServerWebExchangeReactorContextWebFilter [DefaultWebFilterChain]
    |_ checkpoint ⇢ org.springframework.security.web.server.WebFilterChainProxy [DefaultWebFilterChain]
    |_ checkpoint ⇢ HTTP POST "/api/test" [ExceptionHandlingWebHandler]
Stack trace:
        at org.springframework.security.access.prepost.PrePostAdviceReactiveMethodInterceptor.invoke(PrePostAdviceReactiveMethodInterceptor.java:76) ~[spring-security-core-5.3.0.RELEASE.jar:5.3.0.RELEASE]
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747) ~[spring-aop-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:689) ~[spring-aop-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at com.example.demo.handlers.TestHandler$$EnhancerBySpringCGLIB$$71f7a9a3.test(<generated>) ~[main/:na]
        at com.example.demo.RoutingConfig$routes$1$1$1.invoke(RoutingConfig.kt:21) ~[main/:na]
        at com.example.demo.RoutingConfig$routes$1$1$1.invoke(RoutingConfig.kt:16) ~[main/:na]
        at org.springframework.web.reactive.function.server.CoRouterFunctionDsl$asHandlerFunction$1$1.invokeSuspend(CoRouterFunctionDsl.kt:599) ~[spring-webflux-5.2.4.RELEASE.jar:5.2.4.RELEASE]
        at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33) ~[kotlin-stdlib-1.3.70.jar:1.3.70-release-328 (1.3.70)]
        at kotlinx.coroutines.DispatchedContinuationKt.resumeCancellableWith(DispatchedContinuation.kt:314) ~[kotlinx-coroutines-core-1.3.4.jar:na]
        at kotlinx.coroutines.intrinsics.CancellableKt.startCoroutineCancellable(Cancellable.kt:26) ~[kotlinx-coroutines-core-1.3.4.jar:na]
        at kotlinx.coroutines.CoroutineStart.invoke(CoroutineStart.kt:109) ~[kotlinx-coroutines-core-1.3.4.jar:na]
        at kotlinx.coroutines.AbstractCoroutine.start(AbstractCoroutine.kt:158) ~[kotlinx-coroutines-core-1.3.4.jar:na]
        at kotlinx.coroutines.reactor.MonoKt$monoInternal$1.accept(Mono.kt:55) ~[kotlinx-coroutines-reactor-1.3.4.jar:na]
        at kotlinx.coroutines.reactor.MonoKt$monoInternal$1.accept(Mono.kt) ~[kotlinx-coroutines-reactor-1.3.4.jar:na]
        at reactor.core.publisher.MonoCreate.subscribe(MonoCreate.java:57) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:55) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:150) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:67) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoNext$NextSubscriber.onNext(MonoNext.java:76) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.innerNext(FluxConcatMap.java:274) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxConcatMap$ConcatMapInner.onNext(FluxConcatMap.java:851) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:121) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:203) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:203) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2267) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.request(FluxPeekFuseable.java:137) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.request(FluxPeekFuseable.java:137) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.request(FluxMapFuseable.java:162) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2075) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onSubscribe(Operators.java:1949) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onSubscribe(FluxMapFuseable.java:90) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onSubscribe(FluxPeekFuseable.java:171) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onSubscribe(FluxPeekFuseable.java:171) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.Mono.subscribe(Mono.java:4110) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.drain(FluxConcatMap.java:441) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.onSubscribe(FluxConcatMap.java:211) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:161) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:86) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:55) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.Mono.subscribe(Mono.java:4110) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onComplete(FluxSwitchIfEmpty.java:75) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:141) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:67) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxFilter$FilterSubscriber.onNext(FluxFilter.java:107) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxDefaultIfEmpty$DefaultIfEmptySubscriber.onNext(FluxDefaultIfEmpty.java:92) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoNext$NextSubscriber.onNext(MonoNext.java:76) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.innerNext(FluxConcatMap.java:274) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxConcatMap$ConcatMapInner.onNext(FluxConcatMap.java:851) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1705) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:241) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxDefaultIfEmpty$DefaultIfEmptySubscriber.onNext(FluxDefaultIfEmpty.java:92) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:121) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxFilterFuseable$FilterFuseableSubscriber.onNext(FluxFilterFuseable.java:112) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onNext(FluxMapFuseable.java:287) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxFilterFuseable$FilterFuseableConditionalSubscriber.onNext(FluxFilterFuseable.java:330) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1705) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:144) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxFilterFuseable$FilterFuseableSubscriber.onNext(FluxFilterFuseable.java:112) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2267) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxFilterFuseable$FilterFuseableSubscriber.request(FluxFilterFuseable.java:184) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoFlatMap$FlatMapMain.onSubscribe(MonoFlatMap.java:103) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxFilterFuseable$FilterFuseableSubscriber.onSubscribe(FluxFilterFuseable.java:81) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoCurrentContext.subscribe(MonoCurrentContext.java:35) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:55) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:150) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:121) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxFilterFuseable$FilterFuseableSubscriber.onNext(FluxFilterFuseable.java:112) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2267) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxFilterFuseable$FilterFuseableSubscriber.request(FluxFilterFuseable.java:184) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.request(FluxMapFuseable.java:162) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoFlatMap$FlatMapMain.onSubscribe(MonoFlatMap.java:103) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onSubscribe(FluxMapFuseable.java:90) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxFilterFuseable$FilterFuseableSubscriber.onSubscribe(FluxFilterFuseable.java:81) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.Mono.subscribe(Mono.java:4110) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.drain(FluxConcatMap.java:441) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.onSubscribe(FluxConcatMap.java:211) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:161) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:86) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:55) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:55) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.Mono.subscribe(Mono.java:4110) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.drain(MonoIgnoreThen.java:172) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:56) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.Mono.subscribe(Mono.java:4110) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onComplete(FluxSwitchIfEmpty.java:75) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxFilter$FilterSubscriber.onComplete(FluxFilter.java:160) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onComplete(FluxSwitchIfEmpty.java:78) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2269) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2075) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onSubscribe(Operators.java:1949) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.Mono.subscribe(Mono.java:4110) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onComplete(FluxSwitchIfEmpty.java:75) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoNext$NextSubscriber.onComplete(MonoNext.java:96) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxFilter$FilterSubscriber.onComplete(FluxFilter.java:160) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxFlatMap$FlatMapMain.checkTerminated(FluxFlatMap.java:823) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxFlatMap$FlatMapMain.drainLoop(FluxFlatMap.java:589) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxFlatMap$FlatMapMain.drain(FluxFlatMap.java:569) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxFlatMap$FlatMapMain.onComplete(FluxFlatMap.java:455) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxIterable$IterableSubscription.slowPath(FluxIterable.java:289) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxIterable$IterableSubscription.request(FluxIterable.java:225) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxFlatMap$FlatMapMain.onSubscribe(FluxFlatMap.java:363) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:161) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:86) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:55) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:150) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1705) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxDefaultIfEmpty$DefaultIfEmptySubscriber.onComplete(FluxDefaultIfEmpty.java:100) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:136) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxFilter$FilterSubscriber.onComplete(FluxFilter.java:160) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxMap$MapConditionalSubscriber.onComplete(FluxMap.java:262) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1706) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoCacheTime$CoordinatorSubscriber.signalCached(MonoCacheTime.java:320) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.MonoCacheTime$CoordinatorSubscriber.onNext(MonoCacheTime.java:337) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxPeek$PeekSubscriber.onNext(FluxPeek.java:192) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:67) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.publisher.FluxSubscribeOnCallable$CallableSubscribeOnSubscription.run(FluxSubscribeOnCallable.java:249) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.scheduler.SchedulerTask.call(SchedulerTask.java:68) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at reactor.core.scheduler.SchedulerTask.call(SchedulerTask.java:28) ~[reactor-core-3.3.3.RELEASE.jar:3.3.3.RELEASE]
        at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[na:1.8.0_232]
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) ~[na:1.8.0_232]
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) ~[na:1.8.0_232]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) ~[na:1.8.0_232]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) ~[na:1.8.0_232]
        at java.lang.Thread.run(Thread.java:748) ~[na:1.8.0_232]

Comment From: rwinch

Thanks for the detailed sample. I don't think this can work at the moment because the ReactiveSecurityContextHolder leverages Reactor's Context which as far as I know requires the return types to be Mono or Flux at this point. Any method that breaks this chain would mean we would not have access to the Authentication and cannot perform any security checks.

@simonbasle Can you comment if Reactor's Context works with (or could work with) Kotlin Coroutines?

Comment From: simonbasle

IIRC Kotlin Coroutines' have their own concept of context which can be bridged over to Reactor's Context when adapting a Flux/Mono (and should be when using the official bridges IIRC, if that is still a thing). maybe @sdeleuze will have more insight into that.

Comment From: TonCherAmi

Interop between coroutine context and Reactor context should be possible according to this issue kotlin/kotlinx.coroutines#284

Comment From: rwinch

Thanks for the additional details @simonbasle and @TonCherAmi We will look into this one once https://github.com/spring-projects/spring-framework/issues/22462 is addressed.

Comment From: sdeleuze

Indeed we still need to complete the Coroutines story with AOP and annotation based security and transaction support.

@rwinch I will synchronize with you asap we make progress on this issue.

Comment From: sdeleuze

@rwinch @eleftherias I have just merged @Transactional Coroutines support in Spring Framework (see https://github.com/spring-projects/spring-framework/commit/5429c7afebaa3255ea80197224023c29c7d552ec), where the changes should give you some hints about what to do on PrePostAdviceReactiveMethodInterceptor side.

Notice that Coroutines and Reactor conversion is context aware so this is automatically handled, and that you should probably use KotlinDetector.isSuspendingFunction(method) and CoroutinesUtils.invokeSuspendingFunction(...). Make sure to test and support suspending functions returning a Flow which is handled by CoroutinesUtils.invokeSuspendingFunction(...) but could require some extra handling on your side since that a special case that is conceptually equivalent to a Flux.

I don't think updates on Spring AOP side are needed.

Comment From: rt-works

can still confirm the issue in the spring boot 2.4.1

Comment From: danthonywalker

Is there a way we can workaround this by implementing our own PrePostAdviceReactiveMethodInterceptor or something? Or do we just have to for now do fun endpoint(): Mono<Any> = mono {}?

Comment From: rt-works

@danthonywalker

Is there a way we can workaround this by implementing our own PrePostAdviceReactiveMethodInterceptor or something? Or do we just have to for now do fun endpoint(): Mono<Any> = mono {}?

It didn't really work out, did it? For me the same exception.

Comment From: cardechr

Has anyone found a workaround for this?

Comment From: 6oP

@danthonywalker

Is there a way we can workaround this by implementing our own PrePostAdviceReactiveMethodInterceptor or something? Or do we just have to for now do fun endpoint(): Mono<Any> = mono {}?

It didn't really work out, did it? For me the same exception.

Try to remove "suspend" from your endpoint function. mono{} starts new corotine