optimize pay fee detail to month

service-fee/src/main/java/com/java110/fee/feeMonth/PayFeeMonthHelp.java

@@ -187,7 +187,7 @@ public class PayFeeMonthHelp implements IPayFeeMonthHelp {
             }
 
         }
-        return null;
+        return monthFeeDetailDtos;
     }