MongoDB connection does not validate unless non-required field is filled

When filling in the connection details for mongodb, there's a non-requred field Administration database. This field defaults to admin when not filled, which may cause Authentication failed errors when the admin database is not required.

I was able to workaround by specifying the same name as in the database field below, but the experience is very confusing, especially since the value in the field is greyed when not filled.