[BUG] POP3, Email is deleted from the server when calling any function on MimeMultipart Object, even when READ_ONLY is set on folder

[mathias-vandaele]

Describe the bug

When trying to read all the content of an email, the email is deleted.
It seems to happens whatever the function we call on MimeMultipart

To Reproduce
Steps to reproduce the behavior:

    Properties properties = new Properties();
    properties.put("mail.store.protocol", "pop3s");
    properties.put("mail.pop3s.host", "pop.gmail.com");
    properties.put("mail.pop3s.port", "995");
    properties.put("mail.pop3s.auth", true);
    properties.put("mail.pop3s.starttls.enable", true);
    Session session = Session.getInstance(properties);
    Store store = session.getStore();
    store.connect("[email protected]", "password");
    Folder folder = store.getFolder("INBOX");
    folder.open(Folder.READ_ONLY);

    // Let's say we have 20 messages.
    System.out.println("NB of elements: " + folder.getMessageCount());
    Message message = folder.getMessages()[0];
    MimeMultipart mimeMultipart = (MimeMultipart) message.getContent();
    mimeMultipart.getCount();
    folder.close();

    folder.open(Folder.READ_ONLY);
    // We have only 19 messages left
    System.out.println("NB of elements: " + folder.getMessageCount());
    folder.close();

Expected behavior

The email should not be deleted.

Screenshots

Desktop (please complete the following information):

• OS: Mac OS
• Browser NA
• Version NA

Mail server:

• Protocol being used: pop3
• Vendor/product: google
• Mail service URL: gmail.com

Additional context
Add any other context about the problem here.

[jbescos]

Could you run it adding this line and copy paste the output, please?.
properties.put("mail.debug", "true");

I am trying it with this example and it is not removing it https://github.com/jbescos/jakartaEE10MailDemo