code: def _filter_headers(self):
          
          headers = {}
          for user in self.usernames:
              headers["fedora_messaging_user_{}".format(user)] = True
          for package in self.packages:
              headers["fedora_messaging_rpm_{}".format(package)] = True
          for container in self.containers:
              headers["fedora_messaging_container_{}".format(container)] = True
          for module in self.modules:
              headers["fedora_messaging_module_{}".format(module)] = True
          for flatpak in self.flatpaks:
              headers["fedora_messaging_flatpak_{}".format(flatpak)] = True
          return headers
docs: Add headers designed for filtering messages based on objects.
  
          Returns:
              dict: Filter-related headers to be combined with the existing headers