GRAILS-10986 documentation for using custom subclass of RestfulContro…

…ller in @resource annotation

src/en/guide/webServices/REST/restfulControllers/extendingRestfulController.gdoc

@@ -55,4 +55,38 @@ class BookController extends RestfulController {
 
 The example above subclasses @RestfulController@ and overrides the protected @queryForResource@ method to customize the query for the resource to take into account the parent resource.
 
+h4. Using custom subclass of RestfulController with Resource annotation
 
+You can also customize the behaviour of the controller that backs the Resource annotation.
+
+The class must provide a constructor that takes a domain class as it's argument. The second constructor is required for supporting Resource annotation with readOnly=true.
+
+This is a template that can be used for subclassed RestfulController classes used in Resource annotations:
+{code}
+class SubclassRestfulController<T> extends RestfulController<T> {
+    SubclassRestfulController(Class<T> domainClass) {
+        this(domainClass, false)
+    }
+
+    SubclassRestfulController(Class<T> domainClass, boolean readOnly) {
+        super(domainClass, readOnly)
+    }
+}
+{code}
+
+
+You can specify the super class of the controller that backs the Resource annotation with the @superClass@ attribute.
+
+{code}
+import grails.rest.*
+
+@Resource(uri='/books', superClass=SubclassRestfulController)
+class Book {
+
+    String title
+
+    static constraints = {
+        title blank:false
+    }
+}
+{code}