docs: private List<Document> getDistinctCountGroup() {
  		// propertyPath is null when the query is a select on an entity
  		// In this case we can make the distinct on the id of the document
  		Object groupColumn = propertyPath == null ? "$_id" : propertyPath;
  		Document group = new Document();
  		group.append( "$group", new Document( "_id", groupColumn ) );
  
  		Document groupSum = new Document();
  		groupSum.append( "$group", new Document()
  				.append( "_id", propertyPath )
  				.append( PROJECTION_FIELD, new Document( "$sum", 1 ) ) );
  		return Arrays.asList( group, groupSum );
  	}