Add Static Code Analyzers and Style Checkers for the Java parts

# What is currently missing?

There are different ways to write Java (curly braces on same line vs newline, naming conventions), we should programatically decide on the way the project should be written.
Additionally, there are several known bug prone code patterns that we can automatically check and prevent before committing, making our code more secure and in turn reviews are easier to perform.

# How could this be improved?

Last time I worked on Java only codebases there was a triad of plugins to use:
- Spotless (I understand is a better alternative to Checkstyle) -- Already in the project :heavy_check_mark:
- PMD
- SpotBugs (successor of FindBugs)

First, decide on which tools to use (I propose the 3 mentioned above) and configure them with the proper defaults

# Is this a feature you would work on yourself?

* [x] I plan to open a pull request for this feature