def METHOD_NAME():
    with pytest.raises(stix2.exceptions.ExtraPropertiesError) as excinfo:
        stix2.v21.Relationship(my_custom_property="foo", **RELATIONSHIP_KWARGS)
    assert excinfo.value.cls == stix2.v21.Relationship
    assert excinfo.value.properties == ['my_custom_property']
    assert str(excinfo.value) == "Unexpected properties for Relationship: (my_custom_property)."