Well, hot dog dang I don't see support for $$ in MongoDb4Provider.
Ideally I think the provider should be fed a Configuration where the
StrSubstitutor can be accessed.
If you want to provide a failing unit test in that component, I can take a
look at it.
But, I am not sure if that will solve the
If you create a custom Lookup, say CredentialsLookup, when it is called you can
make the same query your factory method did. The result of that would then be
merged into the connections string for Mongo. By the time the Appender would be
resolving that string the Lookup would definitely be avail
