OkHttp perseveres when the network is troublesome: it will silently recover from common connection
problems. If your service has multiple IP addresses, OkHttp will attempt alternate addresses if the
first connect fails. This is necessary for IPv4+IPv6 and services hosted in redundant data
centers. OkHttp supports modern TLS features (TLS 1.3, ALPN, certificate pinning). It can be
configured to fall back for broad connectivity.

    * Two api fields are defined correspondingly:
        * Service.Spec.ExternalTrafficPolicy <- 'service.beta.kubernetes.io/external-traffic' annotation.
        * Service.Spec.HealthCheckNodePort <- 'service.beta.kubernetes.io/healthcheck-nodeport' annotation.

* Cluster federation servers have changed the location in etcd where federated services are stored, so existing federated services must be deleted and recreated. Before upgrading, export all federated services from the federation server and delete the services. After upgrading the cluster, recreate the federated services from the exported data. ([#37770](https://github.com/kubernetes/kubernetes/pull/37770), [@enj](https://github.com/enj))

- the IP allocator in v1.17.0 can return errors such as `the cluster IP <ip> for service <service-name> is not within the service CIDR <cidr>; please recreate` in the logs of the kube-apiserver. The cause is incorrect CIDR calculations if the service CIDR (`--service-cluster-ip-range`) is set to bits lower than `/16`. This is fixed in http://issue.k8s.io/86534 and will be resolved in v1.17.1.

    ExecutorService service = mock(ExecutorService.class);
    application.addDelayedShutdownHook(service, 2, SECONDS);
    verify(service, Mockito.never()).shutdown();
    application.shutdown();
    InOrder shutdownFirst = Mockito.inOrder(service);
    shutdownFirst.verify(service).shutdown();
    shutdownFirst.verify(service).awaitTermination(2, SECONDS);
  }

  [http.routers]

    [http.routers.app-http]
      entryPoints = ["http"]
      service = "app"
      rule = "PathPrefix(`/api/v1`)"
      middlewares = ["api-stripprefix"]

  [http.services]

    [http.services.app]
      [http.services.app.loadBalancer]
        [[http.services.app.loadBalancer.servers]]
          url = "http://127.0.0.1:8000"
```

这个文件配置 Traefik 使用路径前缀 `/api/v1`。

  [http.routers]

    [http.routers.app-http]
      entryPoints = ["http"]
      service = "app"
      rule = "PathPrefix(`/api/v1`)"
      middlewares = ["api-stripprefix"]

  [http.services]

    [http.services.app]
      [http.services.app.loadBalancer]
        [[http.services.app.loadBalancer.servers]]
          url = "http://127.0.0.1:8000"
```

- Added validation to ensure that if `service.kubernetes.io/topology-aware-hints` and `service.kubernetes.io/topology-mode` annotations are both set, they are set to the same value.Also Added deprecation warning if `service.kubernetes.io/topology-aware-hints` annotation is used. ([#116612](https://github.com/kubernetes/kubernetes/pull/116612), [@robscott](https://github.com/robscott))...

 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.api.services;

import java.nio.file.Path;
import java.util.List;
import java.util.Objects;
import java.util.Optional;

import org.apache.maven.api.RemoteRepository;
import org.apache.maven.api.Session;

    /** Session service error class */
    public static final int ERR_SSN_SRVC = 0x02;

    // name service error codes
    /** Format error in the name service */
    public static final int FMT_ERR = 0x1;
    /** Server error in the name service */
    public static final int SRV_ERR = 0x2;
    /** Implementation error in the name service */
    public static final int IMP_ERR = 0x4;
    /** Refused error in the name service */