RpcClient.java get NullPointerException

[tvd12]

In RpcClient.java we have:

          @Override
            public void handleDelivery(String consumerTag,
                                       Envelope envelope,
                                       AMQP.BasicProperties properties,
                                       byte[] body)
                    throws IOException {
                synchronized (_continuationMap) {
                    String replyId = properties.getCorrelationId();
                    BlockingCell<Object> blocker = _continuationMap.get(replyId);
                    _continuationMap.remove(replyId);
                    blocker.set(new Response(consumerTag, envelope, properties, body));
                }
            }

Because, we haven't checked blocker != null, so we get NullPointerException
And
Why we don't use:

 BlockingCell<Object> blocker = _continuationMap.remove(replyId);

instead of

BlockingCell<Object> blocker = _continuationMap.get(replyId);
                    _continuationMap.remove(replyId);

[acogoluegnes]

@tvd12 Can you provide a code snippet that reliably reproduce the NullPointerException? I don't mind making the code more defensive, but I'd like to do it for a reason.

[tvd12]

I have seen NullPointerException when RpcServer received two request with duplicate correlationId from client. It's a mistake from me, but I think anyone are easy to make that mistake, and if we throw an exception with detail message, it's a help for many developers.
Sorry, I fixed a lot of source code and now I don't want rollback them, so I can't provide to you.