As explained in the
Spring documentation, @RestController is shorthand for @Controller and @ResponseBody rolled together. Since both @Controller and @ResponseBody are supported in the App Engine environment, the new Spring 4 @RestController should work as well. If you do receive errors, you can always revert back to using @Controller and @ResponseBody as an alternative.
You can view our
guide on optimizing the Spring Framework for App Engine, as well as the
Mkyong guide for RESTful Spring on App Engine. If you experience any further issues after performing the above, you can provide details about your setup and stack trace to Stack Overflow. Google groups is intended for general discussions rather than 1-on-1 support assistance. You can see our Community Support [1] page for a list of the tags we monitor.
Before posting a question to Stack Overflow it's a good idea to read over the guidelines at 'How do I ask a good question' [2].