title: Migration from log4j 1.x to log4j2
body: <p>Hi I came across some code which is using log4j. I want to move to log4j2. 
  From <a href="http://logging.apache.org/log4j/2.x/manual/migration.html" rel="nofollow">http://logging.apache.org/log4j/2.x/manual/migration.html</a> I came to that log4j-1.2-api.jar can be used. I have following question :</p>
  
  <ol>
  <li><p>In code I have a custom appender (as given in that link I should not use internals of class Appender) is that mean I can't use log4j-1.2-api.jar ?</p></li>
  <li><p>I also want to use asyn logging feature of log4j2 . How do I do that using log4j-1.2-api.jar.</p></li>
  </ol>