Let's do a kick off on the project!

1) When we uploaded photos we set up a relative path... However it only works on a specific machine!

Find out how it would work on every machine (including linux, windows and macOS systems)

2) Response Entity!

In our API responses we are either returning Strings or Voids... However, in API's we return much more than that to Postman or a front-end app! Aside from returning a possible content, we are also returning Headers and a Status Code... Refactor the API to return the appropriate ResponseEntitys!

3) The Service Layer...

We are storing our content in Lists in our Controller classes. This is CLEARLY wrong! Controllers should never deal with business logic. Move these Lists or Sets to the service layer mocking database rows.

4) Purchases!

We already have an API for Companies and Products. Create an API for Purchases like 'Purchase Controller'. What endpoints will make sense? hint: should we have a 'list' of payments by company?