Two @Incoming via smallrye-reactive-messaging causes build errors.

[navkast]

Describe the bug

I'm trying this experimental feature: https://smallrye.io/smallrye-reactive-messaging/smallrye-reactive-messaging/2/advanced/incomings.html using the smallrye-kafka connector.

I consistently get this failure when building the application:

[ERROR] Failed to execute goal io.quarkus:quarkus-maven-plugin:2.1.3.Final:build (default) on project smallrye-kafka-multiple-incomings: Failed to build quarkus application: io.quarkus.builder.BuildException: Build failure: Build failed due to errors
[ERROR] 	[error]: Build step io.quarkus.smallrye.reactivemessaging.deployment.SmallRyeReactiveMessagingProcessor#build threw an exception: javax.enterprise.inject.spi.DefinitionException: SRMSG00052: Invalid method annotated with @Outgoing: org.acme.kafka.processor.Example#process - the method must not be `void`
[ERROR] 	at io.smallrye.reactive.messaging.MediatorConfigurationSupport.validatePublisher(MediatorConfigurationSupport.java:229)
[ERROR] 	at io.smallrye.reactive.messaging.MediatorConfigurationSupport.validate(MediatorConfigurationSupport.java:87)
[ERROR] 	at io.quarkus.smallrye.reactivemessaging.deployment.QuarkusMediatorConfigurationUtil.create(QuarkusMediatorConfigurationUtil.java:105)
[ERROR] 	at io.quarkus.smallrye.reactivemessaging.deployment.SmallRyeReactiveMessagingProcessor.build(SmallRyeReactiveMessagingProcessor.java:393)
[ERROR] 	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[ERROR] 	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
[ERROR] 	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[ERROR] 	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
[ERROR] 	at io.quarkus.deployment.ExtensionLoader$2.execute(ExtensionLoader.java:820)
[ERROR] 	at io.quarkus.builder.BuildContext.run(BuildContext.java:277)
[ERROR] 	at org.jboss.threads.ContextHandler$1.runWith(ContextHandler.java:18)
[ERROR] 	at org.jboss.threads.EnhancedQueueExecutor$Task.run(EnhancedQueueExecutor.java:2449)
[ERROR] 	at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1478)
[ERROR] 	at java.base/java.lang.Thread.run(Thread.java:834)
[ERROR] 	at org.jboss.threads.JBossThread.run(JBossThread.java:501)

Expected behavior

It should work as described in the documentation: it simply processes both messages from the channels in no particular order

Actual behavior

There's a build failure that shows the usage of @Outcoming. I suspect the building of two @Incoming on the same function internally uses an @Outcoming to facilitate this, but the usage of @Outcoming makes the build step fail with Invalid method annotated with @Outgoing: org.acme.kafka.processor.Example#process - the method must not be void

How to Reproduce?

A reproducer is here: https://github.com/navkast/quarkus-reproducer. It's a very simple reproducer amounting to just:

  @Incoming("topic1")
  @Incoming("topic2")
  public CompletionStage<Void> process(Message<String> msg) {
    return msg.ack();
  }

Adding @Blocking or using public void process(String msg) { have the same results.

Output of uname -a or ver

Darwin Kernel Version 20.6.0: Wed Jun 23 00:26:31 PDT 2021; root:xnu-7195.141.2~5/RELEASE_X86_64 x86_64

Output of java -version

openjdk version "11.0.10" 2021-01-19 OpenJDK Runtime Environment (build 11.0.10+9) OpenJDK 64-Bit Server VM (build 11.0.10+9, mixed mode)

Quarkus version or git rev

2.1.3.Final

Build tool (ie. output of mvnw --version or gradlew --version)

Apache Maven 3.8.1 (05c21c65bdfed0f71a2f2ada8b84da59348c4c5d)

[quarkus-bot]

/cc @Ladicek, @cescoffier, @jmartisk, @kenfinnigan, @michalszynkiewicz, @ozangunalp, @phillip-kruger, @radcortez

[cescoffier]

@navkast Quarkus didn't support @Incomings. I just opened a PR to add support for it.

[navkast]

@cescoffier Thank you for looking and for the prompt reply / resolution!