ConcurrentQueryLoader's class javadoc example declares List<QueryError> and calls new ConcurrentQueryLoader(monitor, errors), but no QueryError type and no (Monitor, List) constructor has ever existed in Lucene, so the example has not compiled on any release since the monitor module was added in 8.2.0 (documentation defect)

Finding LFV-1034Area: monitor / ConcurrentQueryLoader (class javadoc example)Priority: lowImpact: minorNovelty: new

AI-assisted finding, confirmed by automated checks, not yet triaged by a human Lucene committer. This site files nothing upstream.

What it shows

The ConcurrentQueryLoader javadoc says 'Use as follows:' and shows a loop that first creates a List<QueryError> errors and passes it to new ConcurrentQueryLoader(monitor, errors). Copied into code, it does not compile on any release: Lucene has no QueryError class, and the only constructors are (Monitor) and (Monitor, int, int); the two lines are left over from Luwak, the project the monitor module was ported from, whose API had both. Written as new ConcurrentQueryLoader(monitor) without the list, the example compiles (the same form the module's own test uses), so only the javadoc is wrong.

Expected vs actual

Expected: The copied example compiles.
Actual: One javac error, cannot find symbol: class QueryError, with assertions on and off, on main and on the 10.6.0 jars.

Files

src/org/apache/lucene/monitor/TestConcurrentQueryLoaderJavadocExample.java (JUnit test)

Run it

Tested on Lucene main e1faeba08bde (2026-11-02): still reproduces.
Tested on Lucene main 645d4fe14a20 (2026-10-28): reproduced.
How to read the outcome: a failing test is the finding reproducing (the failure message states expected against actual).
Seeds: a rerun with the same seed replays the same random choices. Assertions off (-da -dsa -Dtests.asserts=false) is the production-like setting.

# Lucene checkout at the tested commit, built with: ./gradlew --no-daemon assemble   (JDK 25)
LUCENE=/path/to/lucene; V=12.0.0-SNAPSHOT
CP=$LUCENE/lucene/core/build/libs/lucene-core-$V.jar
CP=$CP:$LUCENE/lucene/codecs/build/libs/lucene-codecs-$V.jar
CP=$CP:$LUCENE/lucene/test-framework/build/libs/lucene-test-framework-$V.jar
CP=$CP:$LUCENE/lucene/analysis/common/build/libs/lucene-analysis-common-$V.jar
CP=$CP:$LUCENE/lucene/memory/build/libs/lucene-memory-$V.jar
CP=$CP:$LUCENE/lucene/monitor/build/libs/lucene-monitor-$V.jar
CP=$CP:randomizedtesting-runner-2.9.2.jar:junit-4.13.2.jar:hamcrest-3.0.jar   # test-framework dependencies (Maven Central)
CP=$CP:junit-platform-console-standalone-6.1.3.jar   # JUnit Platform console launcher (Maven Central)

javac -d classes -cp "$CP" $(find src -name '*.java')

# run 1: assertions on, seed DEADBEEF
java -ea -esa --add-modules jdk.incubator.vector --enable-native-access=ALL-UNNAMED -Dtests.seed=DEADBEEF \
     -cp "classes:$CP" org.junit.platform.console.ConsoleLauncher \
     execute --select-class org.apache.lucene.monitor.TestConcurrentQueryLoaderJavadocExample

Gradle alternative: copy the test into the matching module's src/test/ tree of the checkout and run ./gradlew -p lucene/<module> test --tests <class> -Ptests.seed=<seed> (add -Ptests.asserts=false for a run without assertions).

Files shown on the finding page

TestConcurrentQueryLoaderJavadocExample.java

Feedback

Open an issue in lucene-ai-bug-hunt. Please do not open issues or pull requests in apache/lucene about this finding unless a Lucene committer agrees it should be filed.

Snapshot of 2026-11-04. AI-assisted; not yet triaged by a human Lucene committer. Feedback: open an issue in lucene-ai-bug-hunt.