我是軟件開發的新手，一直在嘗試用 Java 開發一個應用程序，以使用 SendGrid 發送多內容電子郵件（純文本和 html 文件），但我只獲取 HTML 文件。請幫我解決這個問題。這是我的代碼。Email from = new Email("[email protected]");String subject = "Sending with SendGrid is Fun";Content content = new Content();content.setType("text/plain");content.setValue("This is a simple text");content.setType("text/html");content.setValue("This is an HTML text");Personalization personalization = new Personalization();Email to = new Email();to.setEmail("[email protected]");personalization.addTo(to);Email to2 = new Email();to2.setEmail("[email protected]");personalization.addTo(to2);Email Cc = new Email();Cc.setEmail("[email protected]");personalization.addCc(Cc);Mail mail = new Mail();mail.setFrom(from);mail.setSubject(subject);mail.addContent(content);mail.addPersonalization(personalization);endGrid sg = new SendGrid("SENDGRID API");Request request = new Request();try {    request.setMethod(Method.POST);    request.setEndpoint("mail/send");    request.setBody(mail.build());    Response response = sg.api(request);    System.out.println(response.getStatusCode());    System.out.println(response.getBody());    System.out.println(response.getHeaders());} catch (IOException ex) {    throw ex;}