I am trying to make a restful controller to upload files. I have seen this and made this controller:
@RestController
public class MaterialController {
When you are using Postman for multipart request then don't specify a custom Content-Type in Header. So your Header tab in Postman should be empty. Postman will determine form-data boundary. In Body tab of Postman you should select form-data and select file type. You can find related discussion at https://github.com/postmanlabs/postman-app-support/issues/576