title: Log4j2 getting logging event
body: <p>I am trying to migrate a small test case (which make sure our logging is working as expected) from log4j-1.6 to log4j- 2.6. What we are doing is passing a map and logging it under Debug level and verifying whether loggingEvent is Debug or not and asserting for expected rendered message. we are doing this way</p>
  
  <pre><code>   final ArgumentCaptor&lt;LoggingEvent&gt; loggingEventCaptor = ArgumentCaptor.forClass(LoggingEvent.class);
  
      verify(mockAppender).doAppend(loggingEventCaptor.capture());
      final LoggingEvent loggingEvent = loggingEventCaptor.getValue();
  
      assertEquals(Level.DEBUG, loggingEvent.getLevel());
      assertEquals("ExpectedMessage", loggingEvent.getRenderedMessage());
  </code></pre>
  
  <p>But came to know appenders and loggingEvents are not in log4j2. But I couldn't find a way to achieve this. Is it possible with log4j2?</p>