How to make comments field mandatory during Reject action in PCS

Summary:

We have built a VBCS form, once the form is filled and submitted, we trigger the PCS workflow via OIC.

The reviewer would log in to the "My Task" page and Approve/Reject the tasks.

We have a requirement to mandatorily put a comment or display a message during Reject action in PCS.

Can someone please let me know if this is possible? I found few answers but it did not mention how to do it.

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Version (include the version you are using, if applicable):

Oracle Integration Gen 2

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