code: public static Optional<ButtonType> alert(String title, String header, String content) {
          return alert(title, header, content, AlertType.INFORMATION);
      }
docs: 弹窗，alertType默认为{@link AlertType#INFORMATION}，modality默认为{@link Modality#NONE}，window默认为null，style默认为{@link
  StageStyle#DECORATED}
  
  @param title 标题
  @param header 信息头
  @param content 内容
  
  @return {@link ButtonType}