Problem

In a webapp uncaught exceptions are handled (logged) by the servlet container (Tomcat in our case).

However, Logback `TeeFilter` has the following code:

try {
    // ... (omitted)
    filterChain.doFilter(teeRequest, teeResponse);
    // ... (omitted) 
} catch (IOException e) {
    e.printStackTrace();
    throw e;
} catch (ServletException e) {
    e.printStackTrace();
    throw e;
}

This causes the stack trace to appear twice in the console (once logged by TeeFilter, and once by Tomcat).

Proposed solution

1. Remove `e.printStackTrace();` statements from `TeeFilter` - it has no responsibility of printing stack traces of exceptions it can not handle
2. Also replace `System.out.println` statements with logging to SLF4J API at INFO level

I'd be happy to raise a PR for this if a new version of logback-access would be released soon after the fix.