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