ckeditor5 using the downcastwriter and the upcastwriter to wrap comments

I’m looking to get ckeditor5 to wrap comments around its own tag rather than a p.

In the source view i’m inputting:

<p>
Some text.
</p>
// Here we have some comments
<p>
Some text 2.
</p>

It becomes

<p>
Some text.
</p>
<p>// Here we have some comments</p>
<p>
Some text 2.
</p>

But I want:

<p>
Some text.
</p>
<comment>// Here we have some comments</comment>
<p>
Some text 2.
</p>

Instead.

And upon downcasting it should become the initial version.

How can I do this by customizing upcast and downcast?