title: logback ThresholdFilter how todo the opposite
body: <p>I need a filter that only passes through everything info and LESS instead of info and more.  I have seen this done somewhere before in logback.  My full xml is here and I want info and less to go to stdout (without writing a filter as I know that was possible somehow)...</p>
  
  <pre><code>&lt;appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender"&gt;
      &lt;filter class="ch.qos.logback.classic.filter.ThresholdFilter"&gt; 
          &lt;level&gt;info&lt;/level&gt;
      &lt;/filter&gt;
  
      &lt;layout class="ch.qos.logback.classic.PatternLayout"&gt;
          &lt;pattern&gt;%date{ISO8601} %X{sessionid}-%X{user} %caller{1} %-4level: %message%n&lt;/pattern&gt;
      &lt;/layout&gt;
  &lt;/appender&gt;
  
  &lt;appender name="STDERR" class="ch.qos.logback.core.ConsoleAppender"&gt;
      &lt;filter class="ch.qos.logback.classic.filter.ThresholdFilter"&gt; 
          &lt;level&gt;warn&lt;/level&gt;
      &lt;/filter&gt;
  
      &lt;layout class="ch.qos.logback.classic.PatternLayout"&gt;
          &lt;pattern&gt;%date{ISO8601} %X{sessionid}-%X{user} %caller{1} %-4level: %message%n&lt;/pattern&gt;
      &lt;/layout&gt;
      &lt;target&gt;System.err&lt;/target&gt;
  &lt;/appender&gt;
  </code></pre>