release: release 0.6.0

[bsbodden]

This PR buttons up the 0.6.0 release. Ups POM versions, apply SonarLint refactoring suggestions:

* 358d474 - refactor: clean up the wording on metamodel generator messages
* 4199a64 - ci: update wordlist for spellchecker action
* 92c821c - docs: add Spring Data Redis dependent version to README
* 704834f - refactor: constructors of an "abstract" class should not be declared "public" (SonarLint java:S5993) 
* 0a18374 - fix: second class type in Pair not properly declared in getFirstGetter
* 7ea1a46 - refactor: optional value should only be accessed after calling isPresent() (SonarLint java:S3655)
* 7556c47 - refactor: "@Override" should be used on overriding and implementing methods (SonarLint java:S1161)
* 3bdc48b - refactor: utility classes should not have public constructors (SonarLint java:S1118)
* b79cc9c - refactor: deprecated code should be removed (java:S1133)
* 31370ae - refactor: "equals(Object obj)" and "hashCode()" should be overridden in pairs (SonarLint java:S1206)
* e67a72c - refactor: boxing and unboxing should not be immediately reversed (SonarLint java:S2153)
* b5ba884 - refactor: "equals(Object obj)" should be overridden along with the "compareTo(T obj)" method (SonarLint java:S1210)
* ab26885 - refactor: boxed "Boolean" should be avoided in boolean expressions (SonarLint java:S5411)
* a2e1b19 - refactor: Strings should not be concatenated using '+' in a loop (SonarLint java:S1643)
* 11fa6df - refactor: consecutive AssertJ "assertThat" statements should be chained (SonarLint java:S5853)
* 03015af - refactor: chained AssertJ assertions should be simplified to the corresponding dedicated assertion (SonarLint java:S5838)
* e96d8be - refactor: lambdas should be replaced with method references (SonarLint java:S1612)
* 7baf520 - refactor: use the diamond operator ("<>") to reduce the verbosity of generics code (SonarLint java:S2293)
* d2d0ea1 - refactor: use Collections.emptyList() instead of Collections.EMPTY_LIST
* 1a62802 - refactor: re-order Java modifiers per conventions
* cabbe17 - docs: add contributors list to README
* 801c3af - release: 0.6.0

[chayim]

Some comments:

1. We're generally removing contributors from READMEs everywhere, as it's a maintenance sink. On the other hand, the release drafter, already includes the contributors on the release. Can you remove from the readme.
2. CI was broken and not reporting back - I've fixed that - but note that CI now fails.Please have a look@bsbodden

Question: Given the goal set of the JDK + how it works, but more importantly not having any OS specific code in here (other than the demos folder)... why run CI across the platforms?

[chayim]

On the merge side - once CI passes, and we're merged to master... master should properly publish snapshots to mavenhub. If that happens - we're good to use the drafter.

[bsbodden]

Some comments:

1. We're generally removing contributors from READMEs everywhere, as it's a maintenance sink. On the other hand, the release drafter, already includes the contributors on the release. Can you remove from the readme.

Ok, done

2. CI was broken and not reporting back - I've fixed that - but note that CI now fails.Please have a look@bsbodden

The issue is that windows and mac do not provide docker out of the box, so for now I remove CI on mac and windows and just use Linux

Question: Given the goal set of the JDK + how it works, but more importantly not having any OS specific code in here (other than the demos folder)... why run CI across the platforms?

Yeah, I don't see a need to run the long, expensive CI on all platforms, isn't Java build once run anywhere, anyways? :-)

[bsbodden]

@chayim @sazzad16 the issue is that Docker needs to be added to the workflow. I'll try to do that and let you know.

[guyroyse]

LGTM