code: public XAttributeContainer createAttributeContainer(String key, XExtension extension) {
  		return new XAttributeContainerImpl(intern(key), extension);
  	}
docs: /* (non-Javadoc)
  @see org.deckfour.xes.factory.XFactory#createAttributeContainer(java.lang.String, org.deckfour.xes.extension.XExtension)