Users have been surprised that the underlying stream is stopped when the EventStream is closed. This could be because example code from a synchronous stream was copied, i.e.

try (RecordingStream r = new RecordingStream()) {
   r.onEvent(...);
   r.start();
}

and made asynchronous by changing r.start() to r.startAsync(), whereby they don't get any events since the stream is closed immediately when the current thread exits the try-with-resources block.

It may make sense to call this out in the javadoc and state in the specification of the EventStream::close method that the stream will be stopped when closed.

Perhaps also add example code where an async stream is started so users can better understand that use case.