presto-spi/src/main/java/io/prestosql/spi/block/SingleRowBlockWriter.java/SingleRowBlockWriter/writeBytes
class SingleRowBlockWriter:    @Override
    public BlockBuilder writeBytes(Slice source, int sourceIndex, int length)
    {
        checkFieldIndexToWrite();
        fieldBlockBuilders[currentFieldIndexToWrite].writeBytes(source, sourceIndex, length);
        return this;
    }