docs: public static InstanceChange<ServiceInstance> toServiceInstanceChange(InstanceChange<ModelServiceInstance> modelInstanceChange){
          Objects.requireNonNull(modelInstanceChange);
          return new InstanceChange<ServiceInstance>(modelInstanceChange.changedTimeMills,
                  modelInstanceChange.serviceName,
                  modelInstanceChange.changeType,
                  modelInstanceChange.from==null?null:toServiceInstance(modelInstanceChange.from),
                  modelInstanceChange.to==null?null:toServiceInstance(modelInstanceChange.to));
      }