(Quick Reference)
                responseFormats
Purpose
Statically defines the supported response formats used by the 
respond method.
Examples
class BookController {
    static responseFormats = ['xml', 'json']    def show(Long id) {
        respond Book.get(id) 
    } 
}Description
The 
responseFormats property is used to define the response formats supported by a controller and in turn used by the 
respond method. The 
respond method uses 
Content Negotiation to respond with the most appropriate content type. See the documentation on 
REST support for more information.