presto-main/src/main/java/io/prestosql/operator/unnest/ArrayUnnester.java/ArrayUnnester/processCurrentPosition
class ArrayUnnester:    @Override
    protected void processCurrentPosition(int requiredOutputCount)
    {
        // Translate indices
        int startElementIndex = columnarArray.getOffset(getCurrentPosition());
        int length = columnarArray.getLength(getCurrentPosition());

        // Append elements and nulls
        getBlockBuilder(0).appendRange(startElementIndex, length);
        appendNulls(requiredOutputCount - length);
    }