presto-spi/src/main/java/io/prestosql/spi/block/AbstractVariableWidthBlock.java/AbstractVariableWidthBlock/writePositionTo
class AbstractVariableWidthBlock:    @Override
    public void writePositionTo(int position, BlockBuilder blockBuilder)
    {
        writeBytesTo(position, 0, getSliceLength(position), blockBuilder);
        blockBuilder.closeEntry();
    }