apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/service/NamespaceBranchService.java/NamespaceBranchService/findBranch
class NamespaceBranchService:  public Namespace findBranch(String appId, String parentClusterName, String namespaceName) {
    return namespaceService.findChildNamespace(appId, parentClusterName, namespaceName);
  }