### Question:
PahoRxMqttMessage implements RxMqttMessage { public static PahoRxMqttMessage create() { return create(new byte[0]); } PahoRxMqttMessage(byte[] payload);  PahoRxMqttMessage(byte[] payload, RxMqttQoS qos);  PahoRxMqttMessage(byte[] payload, RxMqttQoS qos, boolean retained);  PahoRxMqttMessage(MqttMessage mqttMessage); @Override String getTopic(); @Override int getId(); @Override byte[] getPayload(); @Override RxMqttQoS getQoS(); @Override boolean isRetained(); @Override String toString(); static PahoRxMqttMessage create(); static PahoRxMqttMessage create(MqttMessage message); static PahoRxMqttMessage create(String payload); static PahoRxMqttMessage create(String payload, RxMqttQoS qos); static PahoRxMqttMessage create(String payload, RxMqttQoS qos, boolean retained); static PahoRxMqttMessage create(String payload, Charset charset); static PahoRxMqttMessage create(String payload, Charset charset, RxMqttQoS qos); static PahoRxMqttMessage create(
      String payload, Charset charset, RxMqttQoS qos, boolean retained); static PahoRxMqttMessage create(byte[] payload); static PahoRxMqttMessage create(byte[] payload, RxMqttQoS qos); static PahoRxMqttMessage create(byte[] payload, RxMqttQoS qos, boolean retained);  }### Answer:
@Test(expected = NullPointerException.class) public void whenANullMessageIsSuppliedThenAnExceptionIsThrown() { PahoRxMqttMessage.create((MqttMessage) null); }
@Test(expected = NullPointerException.class) public void whenANullStringMessageIsSuppliedThenAnExceptionIsThrown() { PahoRxMqttMessage.create((String) null); }
@Test(expected = NullPointerException.class) public void whenANullByteArrayMessageIsSuppliedThenAnExceptionIsThrown() { PahoRxMqttMessage.create((byte[]) null); }