presto-main/src/main/java/io/prestosql/server/protocol/RowIterable.java/RowIterator/computeNext
class RowIterator:        @Override
        protected List<Object> computeNext()
        {
            position++;
            if (position >= page.getPositionCount()) {
                return endOfData();
            }

            List<Object> values = new ArrayList<>(page.getChannelCount());
            for (int channel = 0; channel < page.getChannelCount(); channel++) {
                Type type = types.get(channel);
                Block block = page.getBlock(channel);
                values.add(type.getObjectValue(session, block, position));
            }
            return Collections.unmodifiableList(values);
        }