Java spring webflux所有api'；s正在提供不受支持的MediaTypeException

我有一个

@springbootplication

，它使用Gson而不是jackson，使用以下转换器：

@Configuration
public class ApplicationConfiguration {

    @Bean
    public GsonBuilder gsonBuilder(){
        final GsonBuilder gsonBuilder = new GsonBuilder();
        // I registerTypeAdapter 's here
        return gson;
    }
}

我现在有了我的控制器（这在所有控制器上都失败了，不仅仅是这个，而且它们的语法相同）

然而，我得到了这个错误

org.springframework.web.reactive.function.UnsupportedMediaTypeException: Content type 'application/json' not supported for bodyType=java.util.LinkedHashMap<?, ?>
at org.springframework.web.reactive.function.BodyInserters.unsupportedError(BodyInserters.java:391)
at org.springframework.web.reactive.function.BodyInserters.lambda$writeWithMessageWriters$11(BodyInserters.java:381)
at java.base/java.util.Optional.orElseGet(Optional.java:369)
at org.springframework.web.reactive.function.BodyInserters.writeWithMessageWriters(BodyInserters.java:381)
at org.springframework.web.reactive.function.BodyInserters.lambda$fromValue$1(BodyInserters.java:98)
at org.springframework.web.reactive.function.server.DefaultServerResponseBuilder$BodyInserterResponse.writeToInternal(DefaultServerResponseBuilder.java:409)
at org.springframework.web.reactive.function.server.DefaultServerResponseBuilder$AbstractServerResponse.writeTo(DefaultServerResponseBuilder.java:351)
at org.springframework.boot.autoconfigure.web.reactive.error.AbstractErrorWebExceptionHandler.write(AbstractErrorWebExceptionHandler.java:311)
at org.springframework.boot.autoconfigure.web.reactive.error.AbstractErrorWebExceptionHandler.lambda$handle$2(AbstractErrorWebExceptionHandler.java:264)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:118)
at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:203)
at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1705)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:144)
at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:67)
at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:67)
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2267)
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2075)
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onSubscribe(Operators.java:1949)
at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54)
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
at reactor.core.publisher.Mono.subscribe(Mono.java:4110)
at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onComplete(FluxSwitchIfEmpty.java:75)
at reactor.core.publisher.Operators.complete(Operators.java:135)
at reactor.core.publisher.MonoEmpty.subscribe(MonoEmpty.java:45)
at reactor.core.publisher.Mono.subscribe(Mono.java:4110)
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:97)
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:100)
at reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onError(FluxOnAssembly.java:390)
at reactor.core.publisher.Operators.error(Operators.java:185)
at reactor.core.publisher.MonoError.subscribe(MonoError.java:52)
at reactor.core.publisher.Mono.subscribe(Mono.java:4110)
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:97)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onError(MonoFlatMap.java:165)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.secondError(MonoFlatMap.java:185)
at reactor.core.publisher.MonoFlatMap$FlatMapInner.onError(MonoFlatMap.java:251)
at reactor.core.publisher.Operators$MonoSubscriber.onError(Operators.java:1752)
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreInner.onError(MonoIgnoreThen.java:235)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onError(MonoFlatMap.java:165)
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onError(Operators.java:1944)
at reactor.core.publisher.Operators.error(Operators.java:185)
at reactor.core.publisher.MonoError.subscribe(MonoError.java:52)
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
at reactor.core.publisher.Mono.subscribe(Mono.java:4110)
at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onComplete(FluxSwitchIfEmpty.java:75)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onComplete(MonoFlatMap.java:174)
at reactor.core.publisher.MonoNext$NextSubscriber.onComplete(MonoNext.java:96)
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.drain(FluxConcatMap.java:359)
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.onSubscribe(FluxConcatMap.java:211)
at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:161)
at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:86)
at reactor.core.publisher.Mono.subscribe(Mono.java:4110)
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.drain(MonoIgnoreThen.java:172)
at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:56)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:150)
at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:67)
at reactor.core.publisher.MonoNext$NextSubscriber.onNext(MonoNext.java:76)
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.innerNext(FluxConcatMap.java:274)
at reactor.core.publisher.FluxConcatMap$ConcatMapInner.onNext(FluxConcatMap.java:851)
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:121)
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2267)
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.request(FluxMapFuseable.java:162)
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2075)
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onSubscribe(Operators.java:1949)
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onSubscribe(FluxMapFuseable.java:90)
at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54)
at reactor.core.publisher.Mono.subscribe(Mono.java:4110)
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.drain(FluxConcatMap.java:441)
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.onSubscribe(FluxConcatMap.java:211)
at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:161)
at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:86)
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:55)
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
at reactor.core.publisher.Mono.subscribe(Mono.java:4110)
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.drain(MonoIgnoreThen.java:172)
at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:56)
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:55)
at reactor.netty.http.server.HttpServerHandle.onStateChange(HttpServerHandle.java:64)
at reactor.netty.tcp.TcpServerBind$ChildObserver.onStateChange(TcpServerBind.java:228)
at reactor.netty.http.server.HttpServerOperations.onInboundNext(HttpServerOperations.java:465)
at reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:90)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:377)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:363)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:355)
at reactor.netty.http.server.HttpTrafficHandler.channelRead(HttpTrafficHandler.java:170)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:377)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:363)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:355)
at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:436)
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:321)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:295)
at io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:251)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:377)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:363)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:355)
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:377)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:363)
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:163)
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:714)
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:650)
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:576)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:493)
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.base/java.lang.Thread.run(Thread.java:834)

org.springframework.web.reactive.function.UnsupportedMediaTypeException:bodyType=java.util.LinkedHashMap不支持内容类型“application/json”
位于org.springframework.web.reactive.function.BodyInserters.UnsupportderRor（BodyInserters.java:391）
位于org.springframework.web.reactive.function.BodyInserters.lambda$writeWithMessageWriters$11（BodyInserters.java:381）
位于java.base/java.util.Optional.orElseGet（Optional.java:369）
位于org.springframework.web.reactive.function.BodyInserters.WriteWithMessageWriter（BodyInserters.java:381）
位于org.springframework.web.reactive.function.BodyInserters.lambda$fromValue$1（BodyInserters.java:98）
位于org.springframework.web.reactive.function.server.DefaultServerResponseBuilder$BodyInserterResponse.writeToInternal（DefaultServerResponseBuilder.java:409）
位于org.springframework.web.reactive.function.server.DefaultServerResponseBuilder$AbstractServerResponse.writeTo（DefaultServerResponseBuilder.java:351）
位于org.springframework.boot.autoconfigure.web.reactive.error.AbstractErrorWebExceptionHandler.write（AbstractErrorWebExceptionHandler.java:311）
位于org.springframework.boot.autoconfigure.web.reactive.error.AbstractErrorWebExceptionHandler.lambda$handle$2（AbstractErrorWebExceptionHandler.java:264）
位于reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext（MonoFlatMap.java:118）
位于reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext（FluxPeekFuseable.java:203）
位于reactor.core.publisher.Operators$MonoSubscriber.complete（Operators.java:1705）
位于reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext（MonoFlatMap.java:144）
位于reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext（FluxSwitchIfEmpty.java:67）
位于reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext（FluxSwitchIfEmpty.java:67）
位于reactor.core.publisher.Operators$ScalarSubscription.request（Operators.java:2267）
位于reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set（Operators.java:2075）
位于reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onSubscribe（Operators.java:1949）
位于reactor.core.publisher.MonoJust.subscribe（MonoJust.java:54）
位于reactor.core.publisher.monoder.subscribe（monoder.java:52）
位于reactor.core.publisher.Mono.subscribe（Mono.java:4110）
位于reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onComplete（FluxSwitchIfEmpty.java:75）
位于reactor.core.publisher.Operators.complete（Operators.java:135）
位于reactor.core.publisher.MonoEmpty.subscribe（MonoEmpty.java:45）
位于reactor.core.publisher.Mono.subscribe（Mono.java:4110）
位于reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError（FluxOnErrorResume.java:97）
位于reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError（FluxOnErrorResume.java:100）
位于reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onError（FluxOnAssembly.java:390）
位于reactor.core.publisher.Operators.error（Operators.java:185）
位于reactor.core.publisher.MonoError.subscribe（MonoError.java:52）
位于reactor.core.publisher.Mono.subscribe（Mono.java:4110）
位于reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError（FluxOnErrorResume.java:97）
位于reactor.core.publisher.MonoFlatMap$FlatMapMain.onError（MonoFlatMap.java:165）
位于reactor.core.publisher.MonoFlatMap$FlatMapMain.secondError（MonoFlatMap.java:185）
位于reactor.core.publisher.MonoFlatMap$flatmainer.onError（MonoFlatMap.java:251）
位于reactor.core.publisher.Operators$MonoSubscriber.onError（Operators.java:1752）
位于reactor.core.publisher.MonoIgnoreThen$ThenIgnoreInner.onError（MonoIgnoreThen.java:235）
位于reactor.core.publisher.MonoFlatMap$FlatMapMain.onError（MonoFlatMap.java:165）
位于reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onError（Operators.java:1944）
位于reactor.core.publisher.Operators.error（Operators.java:185）
位于reactor.core.publisher.MonoError.subscribe（MonoError.java:52）
位于reactor.core.publisher.monoder.subscribe（monoder.java:52）
位于reactor.core.publisher.Mono.subscribe（Mono.java:4110）
位于reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onComplete（FluxSwitchIfEmpty.java:75）
位于reactor.core.publisher.MonoFlatMap$FlatMapMain.onComplete（MonoFlatMap.java:174）
位于reactor.core.publisher.MonoNext$NextSubscriber.onComplete（MonoNext.java:96）
位于reactor.core.publisher.FluxConcatMap$concatmapimediate.drain（FluxConcatMap.java:359）
位于reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.onSubscribe（FluxConcatMap.java:211）
位于reactor.core.publisher.fluxitable.subscribe（fluxitable.java:161）
位于reactor.core.publisher.fluxitable.subscribe（fluxitable.java:86）
位于reactor.core.publisher.Mono.subscribe（Mono.java:4110）
位于reactor.core.publisher.monognoreten$ThenIgnoreMain.drain（monognoreten.java:172）
位于reactor.core.publisher.monognorethen.subscribe（monognorethen.java:56）
位于reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext（MonoFlatMap.java:150）
位于reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext（FluxSwitchIfEmpty.java:67）
位于reactor.core.publisher.MonoNext$NextSubscriber.onNext（MonoNext.java:76）
位于reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.innenext（FluxConcatMap.java:274）
位于reactor.core.publisher.FluxConcatMap$ConcatMapInner.onNext（FluxConcatMap.java:851）
位于reactor.core.publisher.fluxmapfusable$MapFuseableSubscriber.onNext（fluxmapfusable.java:121）
位于reactor.core.publisher.Operators$ScalarSubscription.request（Operators.java:2267）
位于reactor.core.publisher.fluxmapfusable$MapFuseableSubscriber.request（fluxmapfusable.java:162）
位于reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set（Operators.java:2075）
位于reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onSubscribe（Operators.java:1949）
在reactor.core.publish
spring.http.converters.preferred-json-mapper=gson
spring.codec.max-in-memory-size=10MB

org.springframework.web.reactive.function.UnsupportedMediaTypeException: Content type 'application/json' not supported for bodyType=java.util.LinkedHashMap<?, ?>
at org.springframework.web.reactive.function.BodyInserters.unsupportedError(BodyInserters.java:391)
at org.springframework.web.reactive.function.BodyInserters.lambda$writeWithMessageWriters$11(BodyInserters.java:381)
at java.base/java.util.Optional.orElseGet(Optional.java:369)
at org.springframework.web.reactive.function.BodyInserters.writeWithMessageWriters(BodyInserters.java:381)
at org.springframework.web.reactive.function.BodyInserters.lambda$fromValue$1(BodyInserters.java:98)
at org.springframework.web.reactive.function.server.DefaultServerResponseBuilder$BodyInserterResponse.writeToInternal(DefaultServerResponseBuilder.java:409)
at org.springframework.web.reactive.function.server.DefaultServerResponseBuilder$AbstractServerResponse.writeTo(DefaultServerResponseBuilder.java:351)
at org.springframework.boot.autoconfigure.web.reactive.error.AbstractErrorWebExceptionHandler.write(AbstractErrorWebExceptionHandler.java:311)
at org.springframework.boot.autoconfigure.web.reactive.error.AbstractErrorWebExceptionHandler.lambda$handle$2(AbstractErrorWebExceptionHandler.java:264)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:118)
at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:203)
at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1705)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:144)
at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:67)
at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:67)
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2267)
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2075)
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onSubscribe(Operators.java:1949)
at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54)
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
at reactor.core.publisher.Mono.subscribe(Mono.java:4110)
at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onComplete(FluxSwitchIfEmpty.java:75)
at reactor.core.publisher.Operators.complete(Operators.java:135)
at reactor.core.publisher.MonoEmpty.subscribe(MonoEmpty.java:45)
at reactor.core.publisher.Mono.subscribe(Mono.java:4110)
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:97)
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:100)
at reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onError(FluxOnAssembly.java:390)
at reactor.core.publisher.Operators.error(Operators.java:185)
at reactor.core.publisher.MonoError.subscribe(MonoError.java:52)
at reactor.core.publisher.Mono.subscribe(Mono.java:4110)
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:97)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onError(MonoFlatMap.java:165)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.secondError(MonoFlatMap.java:185)
at reactor.core.publisher.MonoFlatMap$FlatMapInner.onError(MonoFlatMap.java:251)
at reactor.core.publisher.Operators$MonoSubscriber.onError(Operators.java:1752)
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreInner.onError(MonoIgnoreThen.java:235)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onError(MonoFlatMap.java:165)
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onError(Operators.java:1944)
at reactor.core.publisher.Operators.error(Operators.java:185)
at reactor.core.publisher.MonoError.subscribe(MonoError.java:52)
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
at reactor.core.publisher.Mono.subscribe(Mono.java:4110)
at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onComplete(FluxSwitchIfEmpty.java:75)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onComplete(MonoFlatMap.java:174)
at reactor.core.publisher.MonoNext$NextSubscriber.onComplete(MonoNext.java:96)
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.drain(FluxConcatMap.java:359)
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.onSubscribe(FluxConcatMap.java:211)
at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:161)
at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:86)
at reactor.core.publisher.Mono.subscribe(Mono.java:4110)
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.drain(MonoIgnoreThen.java:172)
at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:56)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:150)
at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:67)
at reactor.core.publisher.MonoNext$NextSubscriber.onNext(MonoNext.java:76)
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.innerNext(FluxConcatMap.java:274)
at reactor.core.publisher.FluxConcatMap$ConcatMapInner.onNext(FluxConcatMap.java:851)
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:121)
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2267)
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.request(FluxMapFuseable.java:162)
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2075)
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onSubscribe(Operators.java:1949)
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onSubscribe(FluxMapFuseable.java:90)
at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:54)
at reactor.core.publisher.Mono.subscribe(Mono.java:4110)
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.drain(FluxConcatMap.java:441)
at reactor.core.publisher.FluxConcatMap$ConcatMapImmediate.onSubscribe(FluxConcatMap.java:211)
at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:161)
at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:86)
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:55)
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
at reactor.core.publisher.Mono.subscribe(Mono.java:4110)
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.drain(MonoIgnoreThen.java:172)
at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:56)
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:55)
at reactor.netty.http.server.HttpServerHandle.onStateChange(HttpServerHandle.java:64)
at reactor.netty.tcp.TcpServerBind$ChildObserver.onStateChange(TcpServerBind.java:228)
at reactor.netty.http.server.HttpServerOperations.onInboundNext(HttpServerOperations.java:465)
at reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:90)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:377)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:363)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:355)
at reactor.netty.http.server.HttpTrafficHandler.channelRead(HttpTrafficHandler.java:170)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:377)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:363)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:355)
at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:436)
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:321)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:295)
at io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:251)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:377)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:363)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:355)
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:377)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:363)
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:163)
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:714)
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:650)
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:576)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:493)
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.base/java.lang.Thread.run(Thread.java:834)

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <artifactId>testing</artifactId>
    <packaging>pom</packaging>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.5.RELEASE</version>
    </parent>
    <groupId>com.dummy</groupId>
    <version>0.0.1-SNAPSHOT</version>
    <properties>
        <java.version>11</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
            <!-- Exclude the default Jackson dependency -->
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-json</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.9</version>
        </dependency>

        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.8.4</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

@PostMapping("blocked")
public Mono<ResponseEntity<String>> issueIsBlocked() {
    return Mono.just("test")
        .map(s -> new ResponseEntity<>(s, HttpStatus.OK))
        .onErrorResume(Throwable.class, 
            e -> Mono.just(new ResponseEntity<>(e.getMessage(), HttpStatus.INTERNAL_SERVER_ERROR))
         );
}

@Configuration
public class RouterConfig {

    @Bean
    RouterFunction<ServerResponse> home() {
    return route(POST("/blocked"),
            request -> Mono.just("test")
                    .flatMap(s -> ServerResponse.ok().bodyValue(s))
                    .onErrorResume(Throwable.class, e ->
                            ServerResponse.status(HttpStatus.INTERNAL_SERVER_ERROR).bodyValue(e.getMessage())
                    ));
    }