apollo-client/src/main/java/com/ctrip/framework/apollo/util/yaml/YamlParser.java/YamlParser/createYaml
class YamlParser:  private Yaml createYaml() {
    LoaderOptions loadingConfig = new LoaderOptions();
    loadingConfig.setAllowDuplicateKeys(false);
    return new Yaml(new SafeConstructor(), new Representer(), new DumperOptions(), loadingConfig);
  }