apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/service/NamespaceService.java/NamespaceService/findOne
class NamespaceService:  public Namespace findOne(String appId, String clusterName, String namespaceName) {
    return namespaceRepository.findByAppIdAndClusterNameAndNamespaceName(appId, clusterName,
                                                                         namespaceName);
  }