How to make Read only eff based on other eff in PD?

Summary:

Requirement:

AG1 : Attr1

AG2 : Attribute1

Attribute1 should be read only when Attr1 is not Null, it can be editable until Attr1 is null

Checked page composer binding parameter is not available still tried to check with entering expression its not working

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

On Read only of Attribute 1 , tried below expression

#{bindings.Attr1.inputValue !=null}