Motivation:
The HTTP/2 helloworld client example has 2 bugs:
1. HttpResponseHandler has a map which is accessed from multiple threads, but the map is not thread safe.
2. Requests are flushed and maybe completely written and the responses may be received/processed by Netty before an element is inserted into the HttpResponseHandler map. This may result in an 'unexpected message' error even though the message has actually been sent.
Modifications:
- HttpResponseHandler should use a thread safe map
- Http2Client shouldn't flush until entries are added to the HttpResponseHandler map
Result:
Fixes https://github.com/netty/netty/issues/6165.
d771526f8c