docletPath with relative path resolves incorrectly causing AssertionE…

[martinaldrin]

with a relative path is written verbatim to the javadoc options file. The javadoc tool runs from target/reports/testapidocs, so a relative path like target/test-classes resolves to
target/reports/testapidocs/target/test-classes — which doesn't exist. This causes the wrong class to be loaded from the classpath, which on Java 25 triggers a fatal assertion error:

error: fatal error encountered: java.lang.AssertionError: ignored flag: -Xlint:-options

On Java 21 and earlier the wrong class was silently loaded without crashing.

Fix: In AbstractJavadocMojo.getDocletPath(), resolve docletPath entries through JavadocUtil.prunePaths() (which resolves relative paths against project.getBasedir()) instead of passing them verbatim via
unifyPathSeparator(). This is consistent with how other path parameters are already handled.

Note: testJavadocResourcesWithExcludes fails on a second consecutive mvn verify without clean due to a pre-existing stale data/test isolation issue in the suite — unrelated to this fix. mvn clean verify passes.

━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Checklist status:

• ✅ Addresses one issue only
• ✅ Unit test added: JavadocUtilTest.testPrunePathsResolvesRelativePaths() — fails without the fix, passes with it
• ✅ mvn clean verify passes
• ⚠️ Integration tests (mvn -Prun-its verify) — please indicate if you've run these
• ✅ ~10 lines of code change — no ICLA required
• ✅ Licensed under Apache License 2.0

[martinaldrin]

@slachiewicz I guess the failure is not related to my commit, saw similar failure on other PRs as well

[martinaldrin]

@slachiewicz is there any plan for a new release in coming weeks?