public static L2ModificationInstruction modL2Dst(MacAddress addr) {
        checkNotNull(addr, "Dst l2 address cannot be null");
        return new L2ModificationInstruction.ModEtherInstruction(
                L2ModificationInstruction.L2SubType.ETH_DST, addr);
    }
@Test
    public void testModL2DstMethod() {
        final Instruction instruction = Instructions.modL2Dst(mac1);
        final L2ModificationInstruction.ModEtherInstruction modEtherInstruction =
                checkAndConvert(instruction,
                        Instruction.Type.L2MODIFICATION,
                        L2ModificationInstruction.ModEtherInstruction.class);
        assertThat(modEtherInstruction.mac(), is(equalTo(mac1)));
        assertThat(modEtherInstruction.subtype(),
                is(equalTo(L2ModificationInstruction.L2SubType.ETH_DST)));
    }