title: Logback - Logging multiple levels to one file
body: <p>I need to create a file that only logs TRACE and DEBUG events, but I'm unable to make it work (don't know if it's even possible).</p>
  
  <p>Already tried searching for an option to invert the ThresholdFilter or a way to specify multiple levels on a LevelFilter, but with no success.</p>
  
  <p>The only way that I'm thinking to make this work is to create 2 appende, exactly the same from one to another, but with the LevelFilter in one specified to TRACE and the other to DEBUG.</p>
  
  <p>Is there any other way to accomplish this? Because I'm not a big fan of duplicating code/configuration.</p>