code: def link(self, request, uuid=None):
          
  
          service = self.get_object()
  
          if self.request.method == 'GET':
              try:
                  backend = self.get_backend(service)
                  try:
                      resources = backend.get_resources_for_import(**self.get_import_context())
                  except ServiceBackendNotImplemented:
                      resources = []
  
                  page = self.paginate_queryset(resources)
                  if page is not None:
                      return self.get_paginated_response(page)
  
                  return Response(resources)
              except (ServiceBackendError, ValidationError) as e:
                  raise APIException(e)
  
          else:
              serializer = self.get_serializer(data=request.data)
              serializer.is_valid(raise_exception=True)
  
              try:
                  resource = serializer.save()
              except ServiceBackendError as e:
                  raise APIException(e)
  
              resource_imported.send(
                  sender=resource.__class__,
                  instance=resource,
              )
  
              return Response(serializer.data, status=status.HTTP_200_OK)
docs: To get a list of resources available for import, run **GET** against */<service_endpoint>/link/*
          as an authenticated user.
          Optionally project_uuid parameter can be supplied for services requiring it like OpenStack.
  
          To import (link with Waldur) resource issue **POST** against the same endpoint with resource id.
  
          .. code-block:: http
  
              POST /api/openstack/08039f01c9794efc912f1689f4530cf0/link/ HTTP/1.1
              Content-Type: application/json
              Accept: application/json
              Authorization: Token c84d653b9ec92c6cbac41c706593e66f567a7fa4
              Host: example.com
  
              {
                  "backend_id": "bd5ec24d-9164-440b-a9f2-1b3c807c5df3",
                  "project": "http://example.com/api/projects/e5f973af2eb14d2d8c38d62bcbaccb33/"
              }