Microsoft Graph API provides REST services to upload large files to Sharepoint -

https://docs.microsoft.com/en-us/onedrive/developer/rest-api/api/driveitem_createuploadsession?view=odsp-graph-online

Above link provides approach to upload large files in chunks, it has 2 steps -

1. Create upload session - I am able to create upload session in Pega

2. Upload file -

When I upload file in chunks, Graph API expects CONTENT-LENGTH and CONTENT-RANGE as REST Request Header to upload file chunk.  

I am unable to set value for CONTENT-LENGTH and CONTENT-RANGE in Pega. 

Example: If the size of the chunk to upload is 11900 bytes, and I set CONTENT-LENGTH = 11900, somehow Pega is sending CONTENT-LENGTH = 12000.

It is working fine when tested in Postman, but not working through Pega. Please suggest.