#vulnerable code 
                                @Test
    public void testDecodeDisconnection() throws IOException {
        Packet packet = decoder.decodePacket("0::/woot", null);
        Assert.assertEquals(PacketType.DISCONNECT, packet.getType());
        Assert.assertEquals("/woot", packet.getNsp());
    } 
                            #location 4 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Test
    public void testDecodeDisconnection() throws IOException {
        Packet packet = decoder.decodePackets(Unpooled.copiedBuffer("0::/woot", CharsetUtil.UTF_8), null);
        Assert.assertEquals(PacketType.DISCONNECT, packet.getType());
        Assert.assertEquals("/woot", packet.getNsp());
    }