GROOVY-12227: GeneratedDispatcher: avoid runtime class definition so …

[paulk-asert]

…packed closures work in native images

Two layered changes to the GROOVY-12151 packed-closure machinery (GEP-27):

1. ClosureWriter now passes the three dispatch tables as constant bootstrap arguments (CONSTANT_MethodHandle), resolved by the VM's constant pool rather than a runtime Lookup.findStatic -- which under GraalVM native image demanded per-class reflection metadata. Verified: the tracing agent records zero packedDispatch entries for the new bytecode.

2. GeneratedDispatcher.bootstrap keeps the LambdaMetafactory hidden-class adapters on a regular JVM (the JIT-inlining rationale in the class javadoc), but where classes cannot be defined at run time -- native image, detected per link so build-time class init cannot bake in the wrong answer -- it adapts the tables with method-handle-invoking wrappers instead: ordinary bytecode of this class, AOT-compiled into the image. A catch-based fallback covers AOT runtimes the property probe misses. -Dgroovy.packed.dispatch.handles=true forces the wrapper path on a JVM, for parity testing.

Permanent behaviour, no user-facing flag: JVM semantics are unchanged and the fallback engages only where the hidden-class path cannot work. The old 3-arg bootstrap remains for class files from earlier 6.0 snapshots.

Before/after on GraalVM 25.2.4 (native-image 25.0.4): the packed repro previously failed with 'Classes cannot be defined at runtime ... M$$Lambda...'; it now runs correctly (single emitted class, 30MB image, ~12ms total run time). Parity + undeclared-checked-exception propagation covered by PackedDispatcherHandleBundleTest; all existing packed-closure suites green.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 57.14286% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.9715%. Comparing base (7a34d45) to head (6464647).
⚠️ Report is 5 commits behind head on master.

Files with missing lines	Patch %	Lines
...g/codehaus/groovy/runtime/GeneratedDispatcher.java	54.5454%	14 Missing and 1 partial ⚠️

Additional details and impacted files

@@                Coverage Diff                 @@
##               master      #2762        +/-   ##
==================================================
- Coverage     69.9738%   69.9715%   -0.0023%     
- Complexity      35505      35515        +10     
==================================================
  Files            1557       1557                
  Lines          131675     131705        +30     
  Branches        24169      24170         +1     
==================================================
+ Hits            92138      92156        +18     
- Misses          31193      31209        +16     
+ Partials         8344       8340         -4     

Files with missing lines	Coverage Δ
...rg/codehaus/groovy/classgen/asm/ClosureWriter.java	89.7931% <100.0000%> (ø)
...org/codehaus/groovy/vmplugin/v8/IndyInterface.java	83.5165% <100.0000%> (-0.4614%)	⬇️
...g/codehaus/groovy/runtime/GeneratedDispatcher.java	57.6923% <54.5454%> (-29.2642%)	⬇️

... and 6 files with indirect coverage changes

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[testlens-app]

✅ All tests passed ✅

🏷️ Commit: 6464647
▶️ Tests: 108605 executed
⚪️ Checks: 31/31 completed

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[paulk-asert]

Superseded by #2765