docs: public void addExternalDependencies() {
          final Set<Element> components = new HashSet<>();
          getElements().stream()
                  .map(ElementView::getElement)
                  .filter(e -> e instanceof Component)
                  .forEach(components::add);
  
          // add relationships of all other elements to or from our inside components
          for (Relationship relationship : getContainer().getModel().getRelationships()) {
              if (components.contains(relationship.getSource())) {
                  addExternalDependency(relationship.getDestination(), components);
              }
              if (components.contains(relationship.getDestination())) {
                  addExternalDependency(relationship.getSource(), components);
              }
          }
  
          // remove all relationships between elements outside of this container
          getRelationships().stream()
                  .map(RelationshipView::getRelationship)
                  .filter(r -> !components.contains(r.getSource()) && !components.contains(r.getDestination()))
                  .forEach(this::remove);
      }