docs: private ExpressionFactory getExpressionFactory(ELContext context) {
  		Object obj = context.getContext(ExpressionFactory.class);
  		if (obj instanceof ExpressionFactory) {
  			return (ExpressionFactory)obj;
  		}
  		if (defaultFactory == null) {
  			defaultFactory = ExpressionFactory.newInstance();
  		}
  		return defaultFactory;
  	}