Improvements to the API to allow convenience methods for performing String.format(String, Object...) and allow access to the internal logging delegate.
Firstly, to add the String#format(String, Object...) functionality modify the methods (note: only #trace(...) shown):
void trace(Object message, Object... args);
void trace(Object message, Throwable t, Object... args);
This would allow compatiblity with previous versions of the API (although I believe they would still require a re-compile) and help tidy up code.
Secondly, to obtain access to the internal instance of a logger the addition of a #getDeletegate() method.
I can supply the code if required.