docs: @Override
      public void addListeners(TrainingListener... listeners) {
          if (this.trainingListeners == null) {
              setListeners(listeners);
              return;
          } else {
              List<TrainingListener> newListeners = new ArrayList<>(this.trainingListeners);   //To avoid immutable list issues
              Collections.addAll(newListeners, listeners);
              setListeners(newListeners);
          }
  
          if (solver != null) {
              solver.setListeners(this.trainingListeners);
          }
      }