apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/api/AdminServiceAPI.java/NamespaceBranchAPI/createBranch
class NamespaceBranchAPI:    public NamespaceDTO createBranch(String appId, Env env, String clusterName,
        String namespaceName, String operator) {
      return restTemplate
          .post(env, "/apps/{appId}/clusters/{clusterName}/namespaces/{namespaceName}/branches?operator={operator}",
              null, NamespaceDTO.class, appId, clusterName, namespaceName, operator);
    }