be forwarded to.
                      items:
                        properties:
                          destination:
                            description: Destination uniquely identifies the instances
                              of a service to which the request/connection should
                              be forwarded to.
                            properties:

          // notices and transitions to the FAILED state. We do it by calling notifyFailed directly
          // because the service does not monitor the state of the future so if the exception is not
          // caught and forwarded to the service the task would stop executing but the service would
          // have no idea.
          // TODO(lukes): consider building everything in terms of ListenableScheduledFuture then