apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/service/ReleaseHistoryService.java/ReleaseHistoryService/findNamespaceReleaseHistory
class ReleaseHistoryService:  public List<ReleaseHistoryBO> findNamespaceReleaseHistory(String appId, Env env, String clusterName,
                                                            String namespaceName, int page, int size) {
    PageDTO<ReleaseHistoryDTO> result = releaseHistoryAPI.findReleaseHistoriesByNamespace(appId, env, clusterName,
                                                                                          namespaceName, page, size);
    if (result == null || !result.hasContent()) {
      return Collections.emptyList();
    }

    List<ReleaseHistoryDTO> content = result.getContent();
    Set<Long> releaseIds = new HashSet<>();
    for (ReleaseHistoryDTO releaseHistoryDTO : content) {
      long releaseId = releaseHistoryDTO.getReleaseId();
      if (releaseId != 0) {
        releaseIds.add(releaseId);
      }
    }

    List<ReleaseDTO> releases = releaseService.findReleaseByIds(env, releaseIds);

    return transformReleaseHistoryDTO2BO(content, releases);
  }