OIC Generic REST mapping multi-part Form data

Summary:

Hello experts,

I am hoping you can help me resolve this issue mainly because we have never done it this way before in OIC (gen 3).
We have one REST endpoint where we need to send form-data as Request body with following key values and a "file".

For my life, I have not been able to figure out how to do this in OIC mapper. I've tried following

Then mapped the Attachment Reference and Parameter name as " 'file' " and it did not worked.

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