dataweaveMultipartMessage

%dw 2.0
import dw::module::Multipart
output multipart/mixed boundary="-----az1by2cx34dw"
---
{
"parts": {
  "file" : {
    "headers" : {
      "Content-Type" : "application/octet-stream",
      "Content-Disposition" : {
        "name": "tableau_file",
        "filename": "SuperstoreDatasource.tdsx"
       }
       },
    content :  readUrl("classpath://SuperstoreDatasource.tdsx", "application/octet-stream")
    }
  }
}