send method
Send an event with a payload to this PubSub. PubSub ensures each event will be received in onReceive exactly once. This will return a waiting message that gets resolved as soon as it has been received on the server. Use .addListener to wait for messages to resolve.
Implementation
@override
WaitingMessage send(String event, Map<String, dynamic> payload) {
// TODO: implement send
return super.send(getMetadataHash(event), payload);
}