Error 406 on Spring 3+Google App Engine on Android Studio - spring

Question

I am using Google App Engine to develop a backend module provided by Android Studio. I am also using Spring 3 to map URL to class.Although,I have successfully used the combo on Eclipse.But on Android Studio getting a peculiar error(May be because of gradle error).Consider the following files-
build.gradle
buildscript {
repositories {
jcenter()
}
dependencies {
classpath 'com.google.appengine:gradle-appengine-plugin:1.9.18'
}
}
repositories {
jcenter();
}
apply plugin: 'java'
apply plugin: 'war'
apply plugin: 'appengine'
sourceCompatibility = JavaVersion.VERSION_1_7
targetCompatibility = JavaVersion.VERSION_1_7
dependencies {
appengineSdk 'com.google.appengine:appengine-java-sdk:1.9.18'
compile 'javax.servlet:servlet-api:2.5'
compile 'org.springframework:spring-webmvc:4.0.0.RELEASE'
compile 'com.google.code.gson:gson:2.5'
}
appengine {
downloadSdk = true
appcfg {
oauth2 = true
}
}
MyServlet.java . When I am accessing conventional MyServlet the Gson get successfully loaded and returns the required JSON.
public class MyServlet extends HttpServlet {
#Override
public void doGet(HttpServletRequest req, HttpServletResponse resp)
throws IOException {
resp.setContentType("application/json");
Gson gson = new Gson();
Shop sh = new Shop();
sh.setName("Gufran Kurshid");
sh.setAddress("Pitampura new Delhi");
sh.setId(5235);
resp.getWriter().println(gson.toJson(sh));
}
}
MyController.java - A normal controller URL /hello is also easily accessible.But /getDummyJSON which is made to return JSON is giving Error 406.
#Controller
#RequestMapping("/greet")
public class MyController {
#RequestMapping("/hello")
public ModelAndView helloDost() {
ModelAndView modelAndView = new ModelAndView("rat");
modelAndView.addObject("message", "Hello Dost");
return modelAndView;
}
#RequestMapping(value = "/getDummyJSON", produces = MediaType.APPLICATION_JSON_VALUE, method = RequestMethod.GET)
public
#ResponseBody
Map getDummyJSON() {
Map map = new HashMap<String, Object>();
map.put("status", true);
map.put("message", "Hello Friends");
return map;
}
}
My study says the Spring is not able map and load Gson classes.Is there any thing wrong with Android Studio or my Gradle file ?