@Override
      public boolean hasNext() {
        while (true) {
          if (myCurrent.hasNext()) return true;
          if (myNextId < myContainers.size()) {
            myCurrent = myContainers.get(myNextId++).getValueIterator();
          } else {
            return false;
          }
        }
      }
@Override
      public boolean hasNext()