docs: private AggregatedGroupMapping[] extractGroupsArray(Set<D> columnGroups) {
          Set<AggregatedGroupMapping> groupMappings = new HashSet<AggregatedGroupMapping>();
          for (D discriminator : columnGroups) {
              groupMappings.add(discriminator.getAggregatedGroup());
          }
          return groupMappings.toArray(new AggregatedGroupMapping[0]);
      }