presto-main/src/main/java/io/prestosql/operator/aggregation/minmaxby/LongAndBlockPositionStateSerializer.java/LongAndBlockPositionStateSerializer/writeFirstField
class LongAndBlockPositionStateSerializer:    @Override
    void writeFirstField(BlockBuilder out, LongAndBlockPositionValueState state)
    {
        firstType.writeLong(out, state.getFirst());
    }