Sets the .protocol property on the client side web socket to the
value provided here, which should be one of the strings specified in the
protocols parameter when requesting the web socket. This is intended
for clients and servers to specify sub-protocols to use to communicate to
each other.
optional
idleTimeout: number
If the client does not respond to this frame with a
pong within the timeout specified, the connection is deemed
unhealthy and is closed. The close and error event will be emitted.
The default is 120 seconds. Set to 0 to disable timeouts.