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