docs: public void truncate(long newTruncationPoint) {
          if (newTruncationPoint < getFirstDrId()) {
              return;
          }
          final Iterator<Range<Long>> iter = m_map.asRanges().iterator();
          while (iter.hasNext()) {
              final Range<Long> next = iter.next();
              if (end(next) < newTruncationPoint) {
                  iter.remove();
              } else if (next.contains(newTruncationPoint)) {
                  iter.remove();
                  m_map.add(range(newTruncationPoint, end(next)));
                  return;
              } else {
                  break;
              }
          }
          m_map.add(range(newTruncationPoint, newTruncationPoint));
      }