Demo application to demostrate how to handle a Multipart endpoint with JSON request content using Spring Boot 2.X.
gradle build bootRun
This is going to add the endpoint /upload that can be accessed like this.
Simple request without multipart.
http --print HBhb POST :8080/upload a=a b=b
Multipart request.
http --print hb -f POST :8080/upload request@request.json attach@build.gradle attach@settings.gradle