presto-orc/src/main/java/io/prestosql/orc/reader/ListColumnReader.java/ListColumnReader/startRowGroup
class ListColumnReader:    @Override
    public void startRowGroup(InputStreamSources dataStreamSources)
            throws IOException
    {
        presentStreamSource = dataStreamSources.getInputStreamSource(column, PRESENT, BooleanInputStream.class);
        lengthStreamSource = dataStreamSources.getInputStreamSource(column, LENGTH, LongInputStream.class);

        readOffset = 0;
        nextBatchSize = 0;

        presentStream = null;
        lengthStream = null;

        rowGroupOpen = false;

        elementColumnReader.startRowGroup(dataStreamSources);
    }