open fun pongHandler(handler: Handler<Buffer>): WebSocketBase
Set a pong message handler on the connection. This handler will be invoked every time a pong message is received on the server, and can be used by both clients and servers since the RFC 6455 Sections 5.5.2 and 5.5.3 do not specify whether the client or server sends a ping.
Pong frames may be at most 125 bytes (octets).
There is no ping handler since pings should immediately be responded to with a pong with identical content
Pong frames may be received unsolicited.
Return
a reference to this, so the API can be used fluently