I am using Payara 5.191
@Asynchronous
public CompletionStage<String> getAsyncStringCS() {...}
throws this exception when deploying
org.glassfish.deployment.common.DeploymentException: CDI definition failure:Method "getAsyncStringCS" annotated with org.eclipse.microprofile.faulttolerance.Asynchronous does not return a Future. -- Method "getAsyncStringCS" annotated with org.eclipse.microprofile.faulttolerance.Asynchronous does not return a Future.
Dont know since when, but CompletionStage should work at least for MP 2.0?
Works on WLP