@Override
    public int delete(String id) {
        return this.coll.removeById(id).getN();
    }
@Test
    public void deleteThrowsIllegalArgumentExceptionForInvalidObjectId() {
        expectedException.expect(IllegalArgumentException.class);
        expectedException.expectMessage("state should be: hexString has 24 characters");

        decoratorService.delete("NOPE");
    }