[logback-user] How to know the filename used by the appender of a given logger

Within my application I would like to know the filename used by it's logger. I've asked this question before but didn't get an answer. So I will give it another try. I've browsed through the Javadoc of the classes and interfaces where I thought by their name they should be able to provide this piece of information (LoggerContext and Appender to name two of them), but wasn't lucky. Can anyone help here? Ulrich