presto-main/src/main/java/io/prestosql/operator/aggregation/minmaxby/LongAndBlockPositionStateSerializer.java/LongAndBlockPositionStateSerializer/readFirstField
class LongAndBlockPositionStateSerializer:    @Override
    void readFirstField(Block block, int position, LongAndBlockPositionValueState state)
    {
        state.setFirst(firstType.getLong(block, position));
    }