the attachment to be mandatory field in credit memo invoice type

Dear all,

Kindly I want to ask about the feasibility of this task about making the attachment mandatory in AR transactions when the type is Credit Memo (Hint: via the Sandbox Page Composer EL Expression). If It's feasible kindly Send me the rule that I have to put.

Since the customer selected a transaction type that belongs to the Credit Memo class, the attachment should be mandatory.

Important: The rule should be based on the Transaction Type Class: Any Credit Memo type, not static, meaning not only 'CM Issued to Client -> You need to base your rule on the transaction class "Credit Memo".