Detect BND computeIfAbsent CME and provide actionable diagnostic

[gnodet]

Summary

Fixes #12987 — ConcurrentModificationException in BND/maven-bundle-plugin during dependency resolution under Maven 4.

Root Cause

BND's Jar.putResource() (bndlib ≤ 5.0.0) uses TreeMap.computeIfAbsent() with a mapping function that modifies the same TreeMap — it adds ancestor directory entries inside the mapping function:

// aQute.bnd.osgi.Jar.putResource() — bndlib 4.0.0, line 259
Map<String, Resource> s = directories.computeIfAbsent(getDirectory(path), dir -> {
    for (int n = dir.lastIndexOf('/'); n > 0; n = dir.lastIndexOf('/')) {
        dir = dir.substring(0, n);
        if (directories.containsKey(dir)) break;
        directories.put(dir, null);  // ← modifies the same TreeMap!
    }
    return new TreeMap<>();
});

This violates the computeIfAbsent() contract. JDK 17.0.13+ backported explicit CME detection for TreeMap.computeIfAbsent() (JDK-8259535), which correctly rejects this self-modification pattern. Since Maven 4 requires JDK 17+, all Maven 4 users hit this with old BND versions.

The bug was fixed in bndlib 5.1.0 (FELIX-6259, BND PR #3904).

What This PR Does

• Catches ConcurrentModificationException specifically in DefaultBuildPluginManager.executeMojo()
• Detects the known BND stack trace pattern (aQute.bnd.osgi.Jar.putResource)
• Provides a clear, actionable error message:
  • Identifies the root cause (FELIX-6259 + JDK-8259535)
  • Suggests upgrading maven-bundle-plugin to 5.1.9+ or bnd-maven-plugin to 6.0.0+
• For non-BND CMEs, provides general guidance about computeIfAbsent() issues on newer JDKs
• Adds unit tests for the detection logic

Before (cryptic error)

[ERROR] Failed to execute goal org.apache.felix:maven-bundle-plugin:4.0.0:bundle
  on project geronimo-metrics-common:
  Execution default-bundle of goal ... failed. ConcurrentModificationException

After (actionable diagnostic)

[ERROR] Failed to execute goal org.apache.felix:maven-bundle-plugin:4.0.0:bundle
  on project geronimo-metrics-common:
  Execution default-bundle of goal ... failed: ConcurrentModificationException.
  This is a known bug in bndlib versions prior to 5.1.0 (FELIX-6259):
  BND's Jar.putResource() modifies a TreeMap inside its own computeIfAbsent() call,
  which JDK 17.0.13+ now correctly detects (JDK-8259535).
  To fix this, upgrade maven-bundle-plugin to 5.1.9+ or bnd-maven-plugin to 6.0.0+.

Affected Projects

All 7 projects identified in #12987 use old BND versions (bndlib 4.0.0–4.3.0) that predate the fix:

Project	Plugin	BND Version
geronimo-health	maven-bundle-plugin 4.0.0	bndlib 4.0.0
geronimo-metrics	maven-bundle-plugin 4.0.0	bndlib 4.0.0
geronimo-opentracing	maven-bundle-plugin 4.1.0	bndlib 4.1.0
geronimo-config	maven-bundle-plugin 4.2.1	bndlib ~4.3.0
geronimo-jcache-simple	maven-bundle-plugin 4.2.1	bndlib ~4.3.0
aries-journaled-events	bnd-maven-plugin 4.1.0	bndlib 4.1.0
aries-tx-control	bnd-maven-plugin 4.1.0	bndlib 4.1.0

Test plan

• Unit tests for BND CME detection logic (3 tests)
• All existing maven-core tests pass (643 tests)
• Spotless formatting check passes

🤖 Generated with Claude Code

[gnodet]

Closing in favor of the mvnup approach — upgrading the plugin is the right fix, not adding diagnostics to maven-core.