code: synchronized void add(final Container container) {
      final String containerId = container.getId().toString();
      if (this.hasContainer(containerId)) {
        throw new RuntimeException("Trying to add a Container that is already known: " + containerId);
      }
      this.containers.put(containerId, container);
    }
docs: Registers the given container.
  
  @param container
  @throws java.lang.RuntimeException if a container with the same ID had been registered before.