Usage of the DatabasesByServer method of the Config.Databases class

I am trying to get a list of databases using the DatabaseByServer method but I am only getting an empty string. I have not found any useful examples of the proper usage of this class/method.

I have tried 2 formats. First

set dbList=""

set db=##class(Config.Databases).DatabasesByServer("my-host",.dbList)

I also tried:

set db=##class(Config.Databases).DatabasesByServer("my-host",.dbList,"/cachesys/")

In each case dbList is empty string. I can not figure out what I am missing.