Sonar code improvements

[indegro]

Improvements based on sonar:
Package - tlc2.util.

1. Added @ Override
2. Reordered the modifiers to compy with JLS
3. Replaced StringBuffer with StringBuilder (no ref escape, equivalent behaviour)

[lemmy]

Where is this going? You can probably spend your time on more interesting issues.

[indegro]

Hello,

I've decided to read code and try to understand it and meanwhile do some little improvements.
If there is some minor issues that I may take, just let me know.

I would like to help the project

[indegro]

At the moment I have an idea to add edit support for TLA+ spec into IntelliJ Idea, cause it is the main IDE that I use at work.

[lemmy]

I would assume that adding editing support to IntelliJ is the opposite of a minor issue.

#321 is well defined and enclosed from my perspective.

[indegro]

Thanks, let me check what I can do there