I need the groovy text to copy the value of the Item Purchasing Category into IEF

Summary:

in Item Rule Set, I need to copy the value of the Item Purchasing Category into a IEF, when the Item Purchasing Category is changed.

Content (please ensure you mask any confidential information):

I'm able to do the other way around, copy the value of the IEF into the 'Item Purchasing Category'-field.

for client Requirement I need an approval on this field and to do so, this changed value needs to be copied to an IEF.

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Code Snippet (add any code snippets that support your topic, if applicable):