GROOVY-11841: use ConcurrentHashMap for mutable property index maps

[eric-milles]

classPropertyIndex and classPropertyIndexForSuper have elements added after initialization via addMetaBeanProperty and getMetaProperty. Prevent concurrent modification exceptions.

see #2366

[jdaugherty]

Will concurrent hash map usage introduce build reproducibility issues?

[eric-milles]

The keys of the two indexes are super types (CachedClass). The values (Map<String,MetaMethod>) are still ordered.

[eric-milles]

I only see iteration over the outer map for purposes of copying into the super index. All other access is controlled by some external source of order.

[jdaugherty]

Is there a chance this could be back ported to 4.0.x?

[eric-milles]

If the change is acceptable, I should be able to get it back into 4.

[jdaugherty]

Thank you @eric-milles If you can create the branch for the backport, I can retest in 4.x too.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 67.0225%. Comparing base (d0a53bd) to head (db96c92).

Additional details and impacted files

@@              Coverage Diff              @@
##               master      #2367   +/-   ##
=============================================
  Coverage     67.0225%   67.0225%           
+ Complexity      29420      29418    -2     
=============================================
  Files            1382       1382           
  Lines          116152     116146    -6     
  Branches        20465      20466    +1     
=============================================
- Hits            77848      77844    -4     
+ Misses          31814      31812    -2     
  Partials         6490       6490           

Files with missing lines	Coverage Δ
src/main/java/groovy/lang/MetaClassImpl.java	77.9806% <100.0000%> (-0.0183%)	⬇️

... and 3 files with indirect coverage changes

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