presto-spi/src/main/java/io/prestosql/spi/block/AbstractArrayBlock.java/AbstractArrayBlock/getSingleValueBlock
class AbstractArrayBlock:    @Override
    public Block getSingleValueBlock(int position)
    {
        checkReadablePosition(position);

        int startValueOffset = getOffset(position);
        int valueLength = getOffset(position + 1) - startValueOffset;
        Block newValues = getRawElementBlock().copyRegion(startValueOffset, valueLength);

        return createArrayBlockInternal(
                0,
                1,
                new boolean[] {isNull(position)},
                new int[] {0, valueLength},
                newValues);
    }