https://lucene.apache.org/core/10_3_2/grouping/org/apache/lucene/search/grouping/DistinctValuesCollector.html
DistinctValuesCollector (Lucene 10.3.2 grouping API)
declaration: package: org.apache.lucene.search.grouping, class: DistinctValuesCollector
lucenegroupingapi