code: @NonNull
      public final synchronized ChronosListener getListener(final int id) {
          ChronosListener chronosListener = mListeners.get(id);
          if (chronosListener == null) {
              chronosListener = new ChronosListener(id);
              mListeners.put(id, chronosListener);
          }
          return chronosListener;
      }
docs: Gets previously created ServiceConnector by its id.
  
  @param id an id of the saved ServiceConnector
  @return a restored ServiceConnector, or a new one, if there is no saved instance with a given
  id
  @see {@link ChronosListener#getId()}
  @see #createListener()