After upgrading to 1.8.4 (from 1.7.18), my WebSocketPingListener implementation stopped receiving pings.

Stepping through NettyAsyncHttpProvider and reaching line 2349 I saw pendingOpcode remained OPCODE_UNKNOWN (-1), with frame having type org.jboss.netty.handler.codec.http.websocketx.PingWebSocketFrame. It then goes on un-handled and onPing never gets called. (Soon after, binary, text, and close frames are dispatched to listeners properly.)

In case it helps, I've got a socket open to DataSift, and these ping messages were coming through to the listener.