<p>Closes the session by sending a GOAWAY frame with the given error code
and payload.</p>
<p>The GOAWAY frame is sent only once; subsequent or concurrent attempts to
close the session will have no effect.</p>
@param error the error code
@param payload an optional payload (may be null)
@param callback the callback that gets notified when the frame has been sent
@return true if the frame is being sent, false if the session was already closed
<p>Closes the session by sending a GOAWAY frame with the given error code and payload.</p> <p>The GOAWAY frame is sent only once; subsequent or concurrent attempts to close the session will have no effect.</p>
@param error the error code @param payload an optional payload (may be null) @param callback the callback that gets notified when the frame has been sent @return true if the frame is being sent, false if the session was already closed