Split JmxUtils class into smaller classes with similar responsibilities....

... Each extracted class has at least 80% lign coverage.

This refactoring touches a lot of classes, but is very mechanical and introduces only very limited risk of regression.

This PR touches a fairly large number of files. and can be a bit scary. I did my best to be as un-invasive as possible, but failed to control correctly the changes in the order of imports and some automatic formatting. If this is a problem for the reviewer, I will rework this manually. If you have specific rules about comment formatting and order of imports, I'll be glad to implement a check for them to ensure consistency.
Yea, you're totally right. It would probably be better to just get rid of the static's entirely and then use something like Guice to do the injection of the JsonUtils where it is needed. It could even be a singleton injection.