Set and get the interval for sending ping signals. If a ping message is not
answered by a pong message from the peer, the
WebSocket is assumed
disconnected and the connection is closed with a
WebSocketStatus.GOING_AWAY close code. When a ping signal is sent, the
pong message must be received within pingInterval.
There are never two outstanding pings at any given time, and the next ping timer starts when the pong is received.
Set the pingInterval to
null to disable sending ping messages.
The default value is