IssueTracker

A short description of the issue:
Send an email with a single .eml file as an attachment to your gmail account. Gmail API message.getAttachment does not return .eml file. https://developers.google.com/apps-script/reference/gmail/gmail-message#getAttachments(Object)

A small code sample that reliably reproduces the issue.
  let message = GmailApp.getMessageById(messageId);  
  let attachments = message.getAttachments({includeInlineImages: false});

What steps will reproduce the problem?
1. Send an email with a single .eml file as an attachment to your gmail account
2. Open the gmail message
3. Run the above code in the Google Gmail Addon with the id of the opened gmail

What is the expected output? What do you see instead?  If you see error messages, please provide them.
I expect the .eml file is returned from message.getAttachments, but I don't.