Developing a j2ee based product suggestions invited

I am tasked with developing a product called salary calculator it creates a break up of ctc depending upon location grade ect basically the business rules of a company . The requirement is that that multiple companies should be able to use this product ie It should so designed that the clients can input there business rules (configure the product) and it will create the break for that particular client . There should be no coding required for each client once the product has been developed ie we should not be redeveloping the product and coding the bussiness rules when a new client wants to use it . This product will be deployed on hana cloud (I am comfortable with this part) any suggestions regarding the best approach , what frameworks to use if any will be highly appreciated

Thanks Sameer