### Question:
MqttProtocolClientFactory implements ProtocolClientFactory { @Override public String getScheme() { return "mqtt"; } MqttProtocolClientFactory(Config config); @Override String getScheme(); @Override MqttProtocolClient getClient(); @Override CompletableFuture<Void> init(); @Override CompletableFuture<Void> destroy();  }### Answer:
@Test public void getScheme() { assertEquals("mqtt", new MqttProtocolClientFactory(null).getScheme()); }