docs: public boolean addWriter(String logService, LogWriter writer)
  	{
  		if (logService != null && logService.length() > 0) {
  			final LogService l = (LogService) loggers.get(logService);
  			if (l != null)
  				l.addWriter(writer);
  			return l != null;
  		}
  		synchronized (loggers) {
  			writers.add(writer);
  			for (final Iterator i = loggers.values().iterator(); i.hasNext();)
  				((LogService) i.next()).addWriter(writer);
  			return true;
  		}
  	}