Item Number must not be changed when Item Class is changed

Summary:Item Number must not be changed when Item Class is changed

Content (required): We have the below requirement:

Item Class1 - Item Rule 1 Generated to create Item Number - Configured in Item class level

Item Class 2 - Item Rule 1 Generated to create Item Number - Configured in Item class level

During business transaction, i change Item Class 1 to Item Class 2 using Action Menu.

When Item Class 2 is selected as Item Class , Item Number field will be get updated since rule is configured for the subclass.

We should avoid this scenario, Item number must be same even after changing the Item class and Item Number generation rule must not trigger.