Hey,
I suggested to changes to the Jersey client's asynchronous behavior since I was recently implementing a bigger Jersey client application and I did not find the Jersey client to work as expected:
https://github.com/jersey/jersey/pull/38
https://github.com/jersey/jersey/pull/39
I do of course not know if you want to consider my code changes but I strongly suggest to update the Java doc of ClientProperties.ASYNC_THREADPOOL_SIZE since it does not inform about the fact that this property is currently ignored. This is merely noted in a TODO in the source code and thus not as visible as it should be.
Best, Rafael