apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/api/AdminServiceAPI.java/AdminServiceAPI/findPublicNamespaceForAssociatedNamespace
class AdminServiceAPI:    public NamespaceDTO findPublicNamespaceForAssociatedNamespace(Env env, String appId, String clusterName,
        String namespaceName) {
      return
          restTemplate
              .get(env, "apps/{appId}/clusters/{clusterName}/namespaces/{namespaceName}/associated-public-namespace",
                  NamespaceDTO.class, appId, clusterName, namespaceName);
    }