public static GroupInstruction createGroup(final GroupId groupId) {
        checkNotNull(groupId, "GroupId cannot be null");
        return new GroupInstruction(groupId);
    }
@Test
    public void testCreateGroupMethod() {
        final Instruction instruction = Instructions.createGroup(groupId1);
        final Instructions.GroupInstruction groupInstruction =
                checkAndConvert(instruction,
                                Instruction.Type.GROUP,
                                Instructions.GroupInstruction.class);
        assertThat(groupInstruction.groupId(), is(equalTo(groupId1)));
    }