apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/service/NamespaceService.java/NamespaceService/findNamespaces
class NamespaceService:  public List<NamespaceDTO> findNamespaces(String appId, Env env, String clusterName) {
    return namespaceAPI.findNamespaceByCluster(appId, env, clusterName);
  }