private LoggingEvent subLog(LoggingEvent event) {
    return new LoggingEvent(event.getFQNOfLoggerClass(), event.getLogger(), event.getTimeStamp(),
        event.getLevel(), subAppend(event), event.getThreadName(), event.getThrowableInformation(),
        event.getNDC(), event.getLocationInformation(), event.getProperties());
  }
Additional configurations needed before logging to stream. Called once in the container before the first log event is sent.
samza-log4j/src/main/java/org/apache/samza/logging/log4j/StreamAppender.java