Unable to add custom format.

[AndriiTsarenko]

I'm looking for the possibility to add default values to interpolation.
For example, I have this key: 'Hello {user}'
And user in my case is optional.
So what I want to add defaultValue formatter.
And my key should look like 'Hello {user, devaultValue, a user}'
And I didn't find out a way to add such formatter.

[jamuhl]

I'm not too deep into messageformat -> is there something like a custom formatter

[jamuhl]

What I want to say with this...if it's not supported in formatjs - it's not supported here

[AndriiTsarenko]

Ok I see.