code: @Override
      public boolean registerIdentification(Identifiable identifiable) {
          if (identifiable == null || identifiable.getID() == null || identifiable.getID().isEmpty()) return false;
          if (registered.containsValue(identifiable) || registered.containsKey(identifiable.getID())) {
              return false;
          }
          registered.put(identifiable.getID(), identifiable);
          return true;
      }
docs: Registers an Identifiable, ID has to be unique.
  @param identifiable the Identifiable to register
  @return true if registered/already registered or false if the ID is already existing