apollo-common/src/main/java/com/ctrip/framework/apollo/common/dto/GrayReleaseRuleDTO.java/GrayReleaseRuleDTO/GrayReleaseRuleDTO
class GrayReleaseRuleDTO:  public GrayReleaseRuleDTO(String appId, String clusterName, String namespaceName, String branchName) {
    this.appId = appId;
    this.clusterName = clusterName;
    this.namespaceName = namespaceName;
    this.branchName = branchName;
    this.ruleItems = Sets.newHashSet();
  }