code: public void setDefaultAccessController (AccessController controller)
      {
          AccessController oldDefault = _defaultController;
          _defaultController = controller;
  
          // switch all objects from the old default (null, usually) to the new default.
          for (DObject obj : _objects.values()) {
              if (oldDefault == obj.getAccessController()) {
                  obj.setAccessController(controller);
              }
          }
      }
docs: Sets up an access controller that will be provided to any distributed objects created on the
  server. The controllers can subsequently be overridden if desired, but a default controller
  is useful for implementing basic access control policies.