How do I resolve Error 8727 in REST API to upload PDF file?

I want to develop a REST API for uploading PDF files. I started with OPENAPI spec file. When I test, I get error 8727 referencing missing required parameter file.

"{"$c(13,10,9)"""errors"":[ {"$c(13,10,9,9,9)"""code"":8727,"$c(13,10,9,9,9)"""domain"":""%ObjectErrors"","$c(13,10,9,9,9)"""error"":""ERROR #8727: Parameter required: file."","$c(13,10,9,9,9)"""id"":""RESTRequired"","$c(13,10,9,9,9)"""params"":[""file"""$c(13,10,9,9,9)"]"$c(13,10,9,9)"}"$c(13,10,9)"],"$c(13,10,9)"""summary"":""ERROR #8727: Parameter required: file."""$c(13,10)"}"

OpenAPI spec (openapi folder), generated code (pdf folder), test method (test folder) and error message (README) are all captured in this GitHub repo:

oliverwilms/iris-rest

I sent the test request to an Interoperability production to review the request. I copied and pasted beginning and end into the ReadMe file.

I cannot identify what is wrong with my request. How do I generate a valid request? Or how should I update the OpenAPI spec to get it to work?