def METHOD_NAME(ref, test, key):
		r_attributes = getChildAttributeValues(ref, key)
		l_attributes = getChildAttributeValues(test, key)
		if r_attributes and l_attributes:
			if sorted(l_attributes) != sorted(r_attributes):
				return list(set(l_attributes).symmetric_difference(set(r_attributes)))
			return None
		return r_attributes