How to upload a file to GitLap Projects Api File Upload from Angular or Spring Boot App

I am trying to upload a file to git to add it to an issue. The file is generated in an angular frontend I have also a spring backend which could provide the file from an api. So how can I set the file parameter to my spring-backend api Endpoint which looks like https://exampledomain.com/getFile/testfile.txt ? Or is there a best Practise for this case?

Api doku: https://docs.gitlab.com/ee/api/projects.html#upload-a-file