Updated with core changes

components/iot-plugins/iot-base-plugin/org.wso2.carbon.device.mgt.iot.api/src/main/java/org/wso2/carbon/device/mgt/iot/api/GroupManagerService.java

@@ -475,7 +475,7 @@ public class GroupManagerService {
     @GET
     @Consumes("application/json")
     @Produces("application/json")
-    public PaginationResult getDevices(@PathParam("groupId") int groupId,
+    public List<Device> getDevices(@PathParam("groupId") int groupId,
                                        @QueryParam("index") int index,
                                        @QueryParam("limit") int limit) {
         try {