docs: public void start() {
  		boolean succeeded = true;
  		Iterator i = mappingFilesMap.keySet().iterator();
  		while (i.hasNext()) {
  			String mappingName = (String) i.next();
  			String fileName = mappingFilesMap.getProperty(mappingName);
  			System.out.println(new LogEntry("loading mapping '" + mappingName + "' from '" + fileName + '\''));
  			//TODO filename sometimes null
  			IndentedConfigReaderMapping mapping = new IndentedConfigReaderMapping(mappingName, fileName, assembly);
  			succeeded = succeeded && mapping.isLoaded();
  			if (!mapping.isLoaded()) {
  				System.out.println(new LogEntry("loading NOT succeeded", (Serializable) mapping.getLoadMessages()));
  			}
  			mappingMap.put(mappingName, mapping);
  		}
  		loadSucceeded = succeeded;
  		isStarted = true;
  	}