apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/service/NamespaceBranchService.java/NamespaceBranchService/updateBranchGrayRules
class NamespaceBranchService:  @Transactional
  public void updateBranchGrayRules(String appId, String clusterName, String namespaceName,
                                    String branchName, GrayReleaseRule newRules) {
    doUpdateBranchGrayRules(appId, clusterName, namespaceName, branchName, newRules, true, ReleaseOperation.APPLY_GRAY_RULES);
  }