| Name | Description | Type | Package | Framework |
| AbstractAllGroupHeadsCollector | This collector specializes in collecting the most relevant document (group head) for each group that match the query. | Class | org.apache.lucene.search.grouping | Apache Lucene |
| AbstractAllGroupHeadsCollector .GroupHead | Represents a group head. | Class | org.apache.lucene.search.grouping.AbstractAllGroupHeadsCollector | Apache Lucene |