presto-main/src/main/java/io/prestosql/operator/aggregation/AbstractGroupCollectionAggregationState.java/AbstractGroupCollectionAggregationState/toAbsolutePosition
class AbstractGroupCollectionAggregationState:    private long toAbsolutePosition(short blockId, int position)
    {
        return sumPositions.get(blockId) + position;
    }