docs: public boolean offer(E e) {
          if(e == null)
              throw new NullPointerException("null objects are not allowed");
          AddNodeAction<K, E> addAction = new AddNodeAction<K, E>(_key, e);
          try {
              return _storeClient.applyUpdate(addAction);
          } catch(IndexOutOfBoundsException ex) {
              // over-capacity
              return false;
          }
      }