I'm afraid it is currently not possible to upload an avatar for rooms, only for users and the group account itself. This is known requested feature, but I can't confirm if it will be available soon. Although feel free to vote and comment for it at:
...have mention name FirstnameLastname. Fe.: @MaartenCautreels This certainly helps to know who is being mentioned in a conversation. Imagine your colleague sends the following message...
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
You're one step closer to meeting fellow Atlassian users at your local meet up. Learn more about AUGs
We're bringing product updates and pro tips on teamwork to ten cities around the world.Save your spot