The stream window size can correctly become negative after processing the initial SETTINGS_INITIAL_WINDOW_SIZE. Stream specific WINDOW_UPDATE's should not cause a stream reset if the current window size is negative before the positive increment amount is added.
http://cr.openjdk.java.net/~chegar/8207960/webrev.00/ https://bugs.openjdk.java.net/browse/JDK-8207960 -Chris.