I found a nice (and small) Spring sample project on the Interface21 Team Blog.
I learned about @NotNull annotations and how to define/process them in the applicationContext.xml. Also, this is an interesting remark I found about registering PropertyEditors:
The JavaBeans package uses a small little convention to resolve property editors. If a conversion is needed for a specific class, the JavaBeans package searches (amongst other) for a class in the same package named after the to be converted class, appended with ‘Editor’. Therefore, the CarModelEditor does NOT have to be registered; it’s found automatically!
I suggest you download the code and have a look at the xml and java files.