code: def post(self, request, *args, **kwargs):
          
          # Ensure that we check for the 'data' key in the request object before
          # attempting to reference it
          if "data" in request.data:
              # This is a workaround for JSONField not liking blank/null refs
              if "metadata" not in request.data["data"]:
                  request.data["data"]["metadata"] = {}
  
              if "initial_sequence_number" not in request.data["data"]:
                  request.data["data"]["initial_sequence_number"] = request.data[
                      "data"
                  ].get("next_sequence_number")
  
              subscription = SubscriptionSerializer(data=request.data["data"])
              if subscription.is_valid():
                  subscription.save()
                  # Return
                  status = 201
                  accepted = {"accepted": True}
                  return Response(accepted, status=status)
              else:
                  status = 400
                  return Response(subscription.errors, status=status)
          else:
              status = 400
              message = {"data": ["This field is required."]}
              return Response(message, status=status)
docs: Validates subscription data before creating Subscription message