public static Instruction popMpls() {
        return new L2ModificationInstruction.ModMplsHeaderInstruction(
                L2ModificationInstruction.L2SubType.MPLS_POP,
                EthType.EtherType.MPLS_UNICAST.ethType());
    }
@Test
    public void testPopMplsEthertypeMethod() {
        final Instruction instruction = Instructions.popMpls(new EthType(1));
        final L2ModificationInstruction.ModMplsHeaderInstruction pushHeaderInstruction =
                checkAndConvert(instruction,
                                Instruction.Type.L2MODIFICATION,
                                L2ModificationInstruction.ModMplsHeaderInstruction.class);
        assertThat(pushHeaderInstruction.ethernetType().toShort(), is((short) 1));
        assertThat(pushHeaderInstruction.subtype(),
                   is(L2ModificationInstruction.L2SubType.MPLS_POP));
    }