fix: preserve processor path types across conflict resolution

[mariuszs]

Summary

Fixes the issue described in maven-compiler-plugin#1042 (comment): when a dependency is both a direct dep (e.g., modular-jar) and a transitive dep of a processor, ConflictResolver removes the transitive occurrence before TypeDeriver can assign processor path types. The artifact ends up only on --module-path, missing from --processor-module-path.

This builds on PR #11380 which introduced TypeDeriver.

Root cause

ConflictMarker keys on groupId:artifactId:extension:classifier. Since modular-jar and modular-processor both have extension=jar, classifier="", they share the same conflict key. ConflictResolver (which runs before TypeDeriver) picks one winner and removes the loser entirely (verbosity=NONE). TypeDeriver then never sees the transitive processor occurrence.

Fix: two-phase approach (no maven-resolver changes needed)

Phase	Transformer	When	What
1	TypeCollector	Before ConflictResolver	Walks pre-conflict tree, records {GA:ext:cls → derived processor type} in context
2	ProcessorTypeMerger (in TypeDeriver)	After ConflictResolver	Reads context, sets PROCESSOR_TYPE property on surviving nodes that need both paths
3	DefaultDependencyResolverResult	At path assignment	Reads PROCESSOR_TYPE, adds artifact to processor paths too

TypeCollector short-circuits when no processor-type direct deps exist, so builds without processors pay zero cost.

Changes

• New TypeCollector transformer (impl + compat)
• New PROCESSOR_TYPE artifact property in MavenArtifactProperties
• TypeDeriver enhanced with ProcessorTypeMerger inner visitor
• DefaultDependencyResolverResult.addDependency() handles PROCESSOR_TYPE
• MavenSessionBuilderSupplier wires TypeCollector before ConflictResolver

Test plan

• New test TypeDeriverWithConflictResolutionTest.sharedDependencyLosesProcessorType — reproduces the exact scenario and verifies the fix
• Control test typeDeriverAloneWorksCorrectly — proves TypeDeriver logic is correct in isolation
• Existing TypeDeriverTest (2 tests) still pass
• Checkstyle: 0 violations
• End-to-end IT in maven-compiler-plugin@f8a6fd1 (modular-processor-shared-dep) — 3-module project with shared-lib as both modular-jar direct dep and transitive dep of modular-processor, verifies javac compiles successfully

Related

• maven-compiler-plugin#1039 — the original issue (FindException with modular processors)
• maven-compiler-plugin#1042 — compiler-plugin workaround (supplements processor-module-path with module-path entries)
• maven#11380 — introduced TypeDeriver (first step, but doesn't handle the conflict resolution case)