docs: def find_endpoints(self):
          """Find upgrade end-points (i.e nodes without dependents)."""
          plugins = self._load_upgrades(remove_applied=False)
  
          dummy_graph_incoming, graph_outgoing = self._create_graph(plugins, {})
  
          endpoints = {}
          for node, outgoing in six.iteritems(graph_outgoing):
              if not outgoing:
                  repository = plugins[node].repository
                  if repository not in endpoints:
                      endpoints[repository] = []
                  endpoints[repository].append(node)
  
          return endpoints