code: public ContainerView createContainerView(SoftwareSystem softwareSystem, String key, String description) {
          assertThatTheSoftwareSystemIsNotNull(softwareSystem);
          assertThatTheViewKeyIsSpecifiedAndUnique(key);
  
          ContainerView view = new ContainerView(softwareSystem, key, description);
          view.setViewSet(this);
          containerViews.add(view);
          return view;
      }
docs: Creates a container view, where the scope of the view is the specified software system.
  
  @param softwareSystem    the SoftwareSystem object representing the scope of the view
  @param key               the key for the view (must be unique)
  @param description       a description of the view
  @return                  a ContainerView object
  @throws                  IllegalArgumentException if the software system is null or the key is not unique