docs: public void incrementHeadSequenceNumber(ConcurrentSubList.Link link)
                      throws ObjectManagerException
      {
          if (Tracing.isAnyTracingEnabled() && trace.isEntryEnabled())
              trace.entry(this,
                          cclass,
                          "incrementheadSequenceNumber",
                          new Object[] { link });
  
          if (link.next == null) { // This subList is now empty.
              headSequenceNumber++; // Look at another list next time.
          } else { // Still more links in this subList.
              ConcurrentSubList.Link nextLink = (ConcurrentSubList.Link) link.next.getManagedObject();
              // If insertion into the body of the list has taken place,
              // then a sequenceNumber will have been duplicated.
              if (nextLink.sequenceNumber != headSequenceNumber)
                  headSequenceNumber++;
          } // if( firstLink.next == null).
  
          if (Tracing.isAnyTracingEnabled() && trace.isEntryEnabled())
              trace.exit(this,
                         cclass,
                         "incrementHeadSequenceNumber",
                         new Object[] { new Long(headSequenceNumber) });
      }