[MNG-6797] Remember if Maven model problems were encountered in Maven 4

[wilx]

This ports the Maven 3 work from #298 to Maven 4 while preserving compatibility
with rules and plugins that use the legacy MavenSession API.

Maven 4 now retains the model problems reported while discovering the reactor.
The native Session exposes the retained ProblemCollector<ModelProblem> and a
hasModelProblems() convenience method, while the legacy
MavenSession#hasModelProblems() and setModelProblems(boolean) methods bridge
to the same session state. The default native collector is backed by
SessionData, so custom Session implementations and derived sessions share a
writable collector without depending on Maven Core's DefaultSession.

Problems encountered while constructing an external parent or imported BOM are
part of the owning project's model result. Derived model-builder requests
therefore share that result's collector, preserving the collector's limits,
counts, and causes rather than copying problems afterward.

Project-collection problems are retained from the selected discovery result
before -pl and related project trimming, matching Maven 3 behavior. Problems
from a speculative multi-module collection attempt are buffered until that
attempt is selected; if Maven rejects it and falls back to the explicitly
requested POM, those unrelated problems are discarded. Later, unrelated
model-building operations remain outside the session collector's scope.

Binary compatibility is preserved by adding default methods to the native
Session and ProjectsSelector interfaces and retaining the existing project
collection entry points. The session-data helper behind the Session defaults
is package-private.

Fixes #8485.

Verification:

• mvn -pl impl/maven-impl -am -Dtest=DefaultModelBuilderTest -Dsurefire.failIfNoSpecifiedTests=false test
  • 17 tests, 0 failures, 0 errors
• mvn -pl impl/maven-core -am -Dtest=DefaultGraphBuilderTest,DefaultSessionTest -Dsurefire.failIfNoSpecifiedTests=false test
  • 41 tests, 0 failures, 0 errors
• mvn -e -B -V -Prun-its clean install
  • all 90 reactor modules passed
  • 1,049 Core ITs completed, 0 failures, 0 errors, 43 skipped
  • MavenITRememberModelProblemsTest passed
  • Checkstyle, RAT, Spotless, and Japicmp passed

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[gnodet]

Well-structured port of the model-problem retention feature from Maven 3 to Maven 4 with thorough test coverage, proper backward compatibility, and correct thread-safe design. Two minor observations:

1. @since version tag: The @since 3.10.0 tag on hasModelProblems() and setModelProblems() in MavenSession.java is inconsistent with the existing @since 4.0.0 convention used elsewhere in the file. The 3.10.0 was carried over from PR #298 (which targets maven-3.10.x), but since this is the Maven 4 codebase, using @since 4.0.0 (or whatever the target Maven 4 release version is) would be more consistent.

2. Duplicate simple class name: Two new classes named SessionModelProblems are introduced — one package-private in org.apache.maven.api (API module) and one public in org.apache.maven.internal.impl (core module). This would be the first instance in the codebase of the same simple name appearing in both api and internal.impl packages. A distinct name for the impl class (e.g., LegacySessionModelProblems or SessionModelProblemsBridge) would reduce potential confusion for future maintainers.

Neither finding is blocking — the overall design is sound: thread safety via ProblemCollector's concurrent data structures, correct enum mapping, binary compatibility via default methods, proper problem propagation through multi-module collection, and thorough test coverage across unit and integration tests.

This review was generated by an AI agent and may contain inaccuracies. Please verify all suggestions before applying.

Claude Code on behalf of gnodet

[wilx]

The @since 3.10.0 seems appropriate if the 3.x change gets accepted.

[gnodet]

Thanks for the quick follow-up! The rename commit cleanly resolved the duplicate class name concern — the impl class is now SessionModelProblemsBridge, and all references in MavenSession.java, DefaultSession.java, and the class file itself are updated with no stale references.

Regarding @since 3.10.0: your reasoning is sound — the tags are only on MavenSession (the 3.x legacy class), not on the Maven 4 API Session.java, so tagging with the 3.x version they first appear in is defensible.

This review was generated by an AI agent and may contain inaccuracies. Please verify all suggestions before applying.

Claude Code on behalf of gnodet