Cleanup code

[JeromeWolff]

One-line summary

Remove warnings, simplify code

Zalando ticket : ARUHA-XXX (only if appropriate)

Description

A few sentences describing the overall goals of the pull request's commits. I have removed unnecessary "throws" and added missing "final" modifiers. Lambda expressions were simplified. Furthermore, I have simplified five to six queries. There was also a typo.

Review

• [ ] Tests
• [ ] Documentation

Deployment Notes

These should highlight any db migrations, feature toggles, etc.