Javadoc
Resume will cause the Servlet container to send a generic event
to the Servlet, where the request can be processed synchronously
(for example, it is possible to use this to complete the request after
some asynchronous processing is done). This also resumes read events
if they have been disabled using suspend. It is then possible to call suspend
again later. It is also possible to call resume without calling suspend before.
This method must be called asynchronously.