apollo-portal/src/main/java/com/ctrip/framework/apollo/openapi/server/service/ServerNamespaceOpenApiService.java/ServerNamespaceOpenApiService/getNamespace
class ServerNamespaceOpenApiService:  @Override
  public OpenNamespaceDTO getNamespace(String appId, String env, String clusterName,
      String namespaceName) {
    NamespaceBO namespaceBO = namespaceService.loadNamespaceBO(appId, Env.valueOf
        (env), clusterName, namespaceName);
    if (namespaceBO == null) {
      return null;
    }
    return OpenApiBeanUtils.transformFromNamespaceBO(namespaceBO);
  }