Hi Luis,
I got one solution (Idea) : Since the attribute is value type and the FM is used inside the GET method of this attribute so we should not use API on presentation layer . So I am thinking to create one method in the GENIL class and put this FM in this method with FLAG set , then I will call this method from Attributes GET method .
API should be called from GENIL class only.
Please suggest is it good Idea ? 
Thanks & Regards,
Akhilesh Bhagat.