docs: private boolean optimisticInsert(
                                      InsertStack       stack,
                                      Object            new1)
      {
          InsertNodes  point = stack.insertNodes();
          int v1 = _vno;
          if (root() == null)
              return pessimisticNeeded;
  
          if ((v1&1) != 0)
              return pessimisticNeeded;
          synchronized(stack)
          {
          }
  
          try
          {
              findInsert(
                        point,
                        stack,
                        new1);
          }
          catch (NullPointerException npe)
          {
              //No FFDC Code Needed.
              _nullPointerExceptions++;
              return checkForPossibleIndexChange(v1, _vno, npe, "optimisticInsert");
          }
          catch (OptimisticDepthException ode)
          {
              //No FFDC Code Needed.
              _optimisticDepthExceptions++;
              return checkForPossibleIndexChange(v1, _vno, ode, "optimisticInsert");
          }
          synchronized(this)
          {
              if (v1 != _vno)
              {
                  _optimisticInsertSurprises++;
                  return pessimisticNeeded;
              }
  
              _optimisticInserts++;
              if (point.isDuplicate())
                  stack.markDuplicate();
              else
              {
                  _vno++;
                  if ((_vno&1) == 1)
                  {
                      finishInsert(point, stack, new1);
                      _population++;
                  }
                  synchronized(stack)
                  {
                  }
                  _vno++;
              }
          } // synchronized(this)
  
          return optimisticWorked;
      }