### Question:
IODataSampleRxIndicatorWifiPacket extends XBeeAPIPacket { public void setSourceAddress(Inet4Address sourceAddress) { if (sourceAddress == null) throw new NullPointerException(ERROR_SOURCE_ADDRESS_NULL); this.sourceAddress = sourceAddress; } IODataSampleRxIndicatorWifiPacket(Inet4Address sourceAddress, int rssi,
			int receiveOptions, byte[] rfData); static IODataSampleRxIndicatorWifiPacket createPacket(byte[] payload); @Override boolean needsAPIFrameID(); @Override boolean isBroadcast(); void setSourceAddress(Inet4Address sourceAddress); Inet4Address getSourceAddress(); void setRSSI(int rssi); int getRSSI(); void setReceiveOptions(int receiveOptions); int getReceiveOptions(); IOSample getIOSample(); byte[] getRFData(); @Override LinkedHashMap<String, String> getAPIPacketParameters();  }### Answer:
@Test public final void testSetSourceAddressNull() { IODataSampleRxIndicatorWifiPacket packet = new IODataSampleRxIndicatorWifiPacket(sourceAddress, rssi, receiveOptions, data); sourceAddress = null; exception.expect(NullPointerException.class); exception.expectMessage(is(equalTo("Source address cannot be null."))); packet.setSourceAddress(sourceAddress); }