The collation package overview's Danish Sorting example calls Sort.setSort, which was removed in 9.0.0, so the example does not compile; on main it is the one error left on the page after #16904 updated its examples (documentation defect)

Finding LFV-1085Area: analysis-common / collation package documentation (package-info.java 'Example Usages')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

You read the analysis-common collation package overview and copy its Danish Sorting example, which indexes five words with CollationKeyAnalyzer and CollationDocValuesField and sorts the hits in Danish order. You expect it to compile, like the page's Farsi and Turkish examples that #16904 just brought up to date on main; instead javac stops at 'sort.setSort(new SortField("contents", SortField.Type.STRING))' with 'cannot find symbol: method setSort(SortField)', because Sort became immutable and lost setSort in 9.0.0 (LUCENE-9325). Written as 'new Sort(new SortField("contents", SortField.Type.STRING))', the example compiles, runs and returns the documented Danish order A,E,B,D,C.

Expected vs actual

• Expected: The copied example compiles, like the page's Farsi and Turkish examples.
• Actual: One compile error, cannot find symbol: method setSort(org.apache.lucene.search.SortField) at page line 91, with assertions on and off.

Files

• src/org/apache/lucene/collation/TestDanishSortingExample.java (JUnit test)

Run it

• Tested on Lucene main e1faeba08bde (2026-11-02): 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=$CP:randomizedtesting-runner-2.9.2.jar:junit-4.13.2.jar:hamcrest-3.0.jar   # test-framework dependencies (Maven Central)
CP=$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, default flags
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.collation.TestDanishSortingExample

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).

Formal models and scripts this finding's part of the hunt used: collation-pkginfo-danish-example-sort-setsort-after-16904

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.