public static ConfigURI createFromIdAndSource(String configId, ConfigSource source) {
        return new ConfigURI(configId, source);
    }
A Config URI is a class that can be used to encapsulate a config source and a config id into one
object to simplify parameter passing.

@author Ulf Lilleengen
config/src/main/java/com/yahoo/config/subscription/ConfigURI.java