I have found a "bug" in your Info class : Your method "display" is expecting two Strings, but it's not written anywhere (nothing in the Javadoc) that these strings are supposed to be HTML constants.
If I do this :
The application crashes, because in the method "render" of "DefaultInfoConfigDefaultAppearance", you assume, for some reason, that these Strings are HTML constants, which is not enforced anywhere.
Instead, I really think that you should change the header of your "display" method to : "public static void display(SafeHtml title, SafeHtml text)".
Have a good day :)