code: public final void addListener(
              @NonNull final Listener<DataType, KeyType, ViewType, ParamType> listener) {
          listeners.add(listener);
      }
docs: Adds a new listener, which should be notified about the events of the data binder.
  
  @param listener
  The listener, which should be added, as an instance of the type {@link Listener}. The
  listener may not be null