How to upload file to inbox in EPBCS using REST API through groovy Business Rule?

Summary:

we are trying to upload file to inbox in EPBCS using REST API through groovy Business Rule. we are struggling on how to define the file path which is on the server and the script should read the path and upload it to the inbox. I understand there is an example of this using REST API but path is not defined if the path is on a server. Please advise.

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