### Question:
UdpConnectionMap { public static MessageConsumer getMessageConsumer(InetSocketAddress address) { if(address == null){ throw new IllegalArgumentException("Address can not be null"); } return connectionMap.get(address); } private  UdpConnectionMap(); static MessageConsumer getMessageConsumer(InetSocketAddress address); static void addConnection(InetSocketAddress address, MessageConsumer consumer); static void removeConnection(InetSocketAddress address);  }### Answer:
@Test(expected = IllegalArgumentException.class) public void testWithoutSenderAddressOnGet(){ UdpConnectionMap.getMessageConsumer(null); }