Nb-Chat not showing user avatar

I'm submitting a ...** (check one with "x")

* [ X] bug report
* [ ] feature request

**Current behavior:**
I can not get a user avatar to show. I also see the same behavior on the Nebular's own example website https://www.akveo.com/ngx-admin/pages/extra-components/chat

**Expected behavior:**
I expected to show an avatar for sender and receiver on the screen. Is this not true.

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Example from my own code.
```
this.messages.push({
text: event.message,
date: new Date(),
reply: true,
type: files.length ? 'file' : 'text',
files: files,
user: {
name: this.kmUser.displayName,
avatar: 'https://i.ytimg.com/vi/Erqi5ckVoEo/hqdefault.jpg',
},
});
```