ZShape is not static so it requires an instance of the outer class.
The simplest solution is to make ZShape and any nested class static if you can.
I would also make any fields final or static final that you can as well.
Suppose RetailerProfileModel is your Main class and RetailerPaymentModel is an inner class within it. You can create an object of the Inner class outside the class as follows:
RetailerProfileModel.RetailerPaymentModel paymentModel
= new RetailerProfileModel().new RetailerPaymentModel();