apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/grayReleaseRule/GrayReleaseRulesHolder.java/GrayReleaseRulesHolder/assembleReversedGrayReleaseRuleKey
class GrayReleaseRulesHolder:  private String assembleReversedGrayReleaseRuleKey(String clientAppId, String
      clientNamespaceName, String clientIp) {
    return STRING_JOINER.join(clientAppId, clientNamespaceName, clientIp);
  }