Avoid .java regeneration when source model file is not modified

[neofreko]

My projects keep generating the test source files on every build although model files was not touched. Turned out, isModified method keeps returning true.

This PR change isModified comparison to use milliseconds comparison instead of native equals method from FileTime class.

While also:

1. Upgrade reflection library due to After migrating to 0.9.12, Getting exception : org.reflections.RflectionException: Scanner SubTypeScanner was not configured , even after configuring the scanner. ronmamo/reflections#273
2. Memoized list of class loaders and context loaders as it is getting called on each processed file.
3. Added tests for SimpleCache
4. Added tests CodeGenerator fix
5. Minor adjustments

The following out was produced for 299 model files by mvn graphwalker:generate-test-sources.

Before:

[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  09:51 min
[INFO] Finished at: 2022-08-09T11:23:34+09:00
[INFO] ------------------------------------------------------------------------

After:

[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  6.173 s
[INFO] Finished at: 2022-08-09T11:27:03+09:00
[INFO] ------------------------------------------------------------------------

[KristianKarl]

Hi @afathonih!
Thanks for the PR Akhmad 👍

I have a question about JitPack. How is it related to the regeneration of java source files issue? Could the 2topics be separated into 2 PRs instead?

Best Kristian

[neofreko]

Hi @KristianKarl ,
I will remove Jitpack bits tomorrow.
I was trying to put the artifact on Jitpack but maven plugin does not work straight forward there.
Thanks for checking the PR.