[ADD] account_payment_pro: add metohd to compute payment diference

account_payment_pro/models/account_payment.py

@@ -391,12 +391,13 @@ def _compute_amount_company_currency_signed_pro(self):
             else:
                 payment.amount_company_currency_signed_pro = payment.amount_company_currency
 
+    def _get_payment_difence(self):
+        return self.to_pay_amount - self.amount_company_currency_signed_pro
+
     @api.depends('to_pay_amount', 'amount_company_currency_signed_pro')
     def _compute_payment_difference(self):
         for rec in self:
-            # if rec.payment_subtype != 'double_validation':
-            #     continue
-            rec.payment_difference = rec.to_pay_amount - rec.amount_company_currency_signed_pro
+            rec.payment_difference = rec._get_payment_difence()
 
     @api.depends('to_pay_move_line_ids.amount_residual')
     def _compute_selected_debt(self):