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

[Ulrich]

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