Extract email attachments and send data to SuccessFactors

Hi All,

I need to extract an Excel file from an email as an attachment and convert it to JSON, then dynamically set the data and send it to SuccessFactors. I can do it manually via Message Body in Content Modifier, but I need to dynamically set data directly from Excel step like this. My manual example is here:

How to insert data dynamically? Can I write Groovy script in Content Modifier Message Body? (I'm new to SAP BTP field) i made like example in below, but it doesn't seem to be working.

Regards