我必须发送电子邮件与thymeleaf模板内，但我收到了明确的html代码没有所需的参数（链接）。我的错在哪里？
方法：

private void sendLetter(User user, String subject, String link, String templatePath, Locale locale) {
    Context ctx = new Context(locale);
    ctx.setVariables(Collections.singletonMap("link", link));
    String htmlContent = templateEngine.process(templatePath, ctx);
    MimeMessage mimeMessage = javaMailSender.createMimeMessage();
    try {
        MimeMessageHelper message = new MimeMessageHelper(mimeMessage, true, "UTF-8");
        message.setTo(user.getEmail());
        message.setFrom(emailProperties.getFrom());
        message.setSubject(subject);
        message.setText(htmlContent, true);
    }
    catch (MessagingException e) {
        e.printStackTrace();
    }

    javaMailSender.send(mimeMessage);
}

主题：

<a class="main_button" href="${link}">