Description

Riot clients remove an existing display name by setting an empty string ("").
If that happens on live, matrix clients will be likely to compute a display name like "Bob and 3 others" as specced by the room summary.
But if a matrix client does an initial sync, it will give an "Empty room" name to the room because it receives no heroes.

Steps to reproduce

On a Riot client:

• create a room with people in there
• set a room display name
• remove it
• Do an initial /sync by clearing the cache.

-> The room will be named "Empty room" instead of "Bob and 3 others" or stg.