[Anshuman-Prakash]

What does this PR do?

Fixes #4593

Log4J2_7PlusLogCorrelationInstrumentation is selected for log4j-core >= 2.7, but its helper cleaned up the correlation IDs with ThreadContext.removeAll(Iterable), which Log4j only added in 2.8. On 2.7 every logging event during a transaction therefore threw NoSuchMethodError from the advice. Because the advice suppresses it, the correlation keys were never removed, so a stale error.id leaked onto later log lines.

• Log4j2_7PlusLogCorrelationHelper.removeFromMdc() now removes the keys one by one with ThreadContext.remove(String), as the 2.6 helper already does. putAll(Map) (available since 2.7) is still used to add them.
• Log4j2InstrumentationTest now also runs the instrumentation and error-capture definitions against Log4j 2.7, next to 2.6, 2.17.1 and 2.24.0.

Tests

Run in maven:3.9-eclipse-temurin-17 (Linux):

mvn -pl apm-agent-plugins/apm-logging-plugin/apm-log4j2-plugin-tests -am install -DskipTests
mvn -pl apm-agent-plugins/apm-logging-plugin/apm-log4j2-plugin-tests test -Dtest=Log4j2InstrumentationTest

• Without the fix (test change only): Tests run: 8, Failures: 1. testInstrumentation[2] (2.7) fails in verifyErrorCaptureAndCorrelation with expected: null but was: "16e9e1523a…" (a leaked error.id), and the log shows the NoSuchMethodError: ThreadContext.removeAll(java.lang.Iterable) from the issue.
• With the fix: Tests run: 8, Failures: 0, Errors: 0, and there is no NoSuchMethodError in the output.

Checklist

• This is an enhancement of existing features, or a new feature in existing plugins
• This is a bugfix
  • I have updated CHANGELOG.next-release.md
  • I have added tests that would fail without this fix
• This is a new plugin
• This is something else

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[Copilot]

🟢 Approval recommended

The narrow compatibility fix preserves cleanup behavior and adds regression coverage for the affected Log4j version, with no unresolved findings.

No open issues 🎉

What changed in this PR

Fixes #4593 by making log-correlation cleanup compatible with Log4j 2.7, preventing NoSuchMethodError and stale correlation IDs.

Changes:

• Replaces bulk key removal with compatible per-key removal while retaining bulk insertion.
• Adds Log4j 2.7 to the instrumentation and error-capture test matrices.
• Documents the compatibility fix in the changelog.

File	Description
CHANGELOG.next-release.md	Records the Log4j 2.7 compatibility fix.
apm-agent-plugins/​apm-logging-plugin/​apm-log4j2-plugin/​src/​main/​java/​co/​elastic/​apm/​agent/​log4j2/​correlation/​Log4j2_7PlusLogCorrelationHelper.java	Uses compatible per-key cleanup and explains the API constraint.
apm-agent-plugins/​apm-logging-plugin/​apm-log4j2-plugin-tests/​src/​test/​java/​co/​elastic/​apm/​agent/​log4j2/​Log4j2InstrumentationTest.java	Adds Log4j 2.7 coverage to both test matrices.

_{Review effort: Balanced}