title: How do I find which class is printing an error?
body: <p>I have a Java program, using Vertx 2, and when I run it, I get a message:</p>
  
  <pre><code>% vertx run -cluster com.abc.prep.manager.PrepStartup -cp ./build/libs/Operational-all-1.0.jar -conf safe.conf
  Starting clustering... 
  No cluster-host specified so using address 172.17.0.1 
  [Fatal Error] :6:3: The element type "hr" must be terminated by the matching end-tag "&lt;/hr&gt;".
  Prep Starting up!
  Succeeded in deploying verticle 
  </code></pre>
  
  <p>I cannot figure out where that '[Fatal Error]' message is coming from.  If someone knows what vertx is doing (since I think it's coming from there), that would be great.</p>
  
  <p>But my real question is:  How do I find out who is printing that?  What class in which jar?  I can't seem to set a breakpoint in System.out or System.err that catches it (I'm using Intellij).  Can I override (all) output so that it prints a stacktrace?  </p>