Cannot add “minlength” tag to textarea in HTML mode

Hi,

I use WYSIWYG editor, and I’d like to add a “minlength” attribute to textarea in HTML mode, but the Publii remove it after I save changes.

Reproduce the issue:

1. Open a new post with WYSIWYG editor
2. Switch to HTML mode
3. Add this code:

   <form><textarea minlength="5"></textarea> <input type="submit" value="Check"></form>

4. Press “Apply changes”
5. Go back to HTML editor
6. You will see the code without the minlength attribute:

   <form><textarea></textarea> <input type="submit" value="Check"></form>

Is it a bug? How can I add “minlength” attribute to textarea?

Thank you!

Feriman