apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/component/emailbuilder/ConfigPublishEmailBuilder.java/ConfigPublishEmailBuilder/cutOffString
class ConfigPublishEmailBuilder:  private String cutOffString(String source) {
    if (source.length() > VALUE_MAX_LENGTH) {
      return source.substring(0, VALUE_MAX_LENGTH) + "...";
    }
    return source;
  }