getMqtt function
Implementation
IMqtt? getMqtt(String url, IMqttListener listener,
{String? username, String? password}) =>
MqttWeb(url, listener, username: username, password: password);
IMqtt? getMqtt(String url, IMqttListener listener,
{String? username, String? password}) =>
MqttWeb(url, listener, username: username, password: password);