send method
Send message data to a connection, referenced by its connectionId.
Implementation
Future<void> send(String connectionId, String data) async {
var req = $wp.WebsocketSendRequest(
socketName: name, connectionId: connectionId, data: utf8.encode(data));
await ClientChannelSingleton.useClient($wp.WebsocketClient.new,
(client) async => await client.sendMessage(req));
}