【异常】SpringBoot中使用JavaMailSender发送带附件的邮件失败

在使用JavaMailSender发送带附件的邮件时，报下面所示异常

java.lang.IllegalStateException: Not in multipart mode - create an appropriate MimeMessageHelper via a constructor that takes a 'multipart' flag if you need to set alternative texts or add inline elements or attachments.

代码：

@Test
    public void sendAttachmentMail() throws MessagingException {
   

        MimeMessage mimeMessage = mailSender.createMimeMessage(