...you (unsurprisingly) get this dialog box to type the new name:
However, the Refactoring window shows you that not only the Java class and its reference in the Java application class will be renamed, but also its corresponding HTML file (highlighted below):
After that, you can also undo the rename action, which will result in both the Java class and the HTML file reverting to their original names:
In addition, when you move a Java class, its corresponding HTML file will be moved too, as can be seen in the screenshot below:
I think these are pretty useful features when you're working with Wicket, because they allow you to treat the Java side and the HTML side together as a single file. Only at the end, when you hand off the HTML side to an HTML designer, only at that stage do the two sides truly separate from each other. Until that point, they need to be kept synchronized, but with as little overhead as possible. The features above go a long way to make that possible.