[minor] make abstract method regular instead of italic

[gayanper]

Make the abstract methods non italic so code which heavily use collection apis and stream apis look better.

[AObuchow]

I hadn't yet considered this - may it's cause of the font I use.

I'll try disabling it and see how it looks when I have a moment.

Feel free to submit a picture showing with/without italics so I can see the difference.