Modify application retrieval API

As per the API designing best practices, added offset and limit query parameters for application getting API.

components/application-mgt/org.wso2.carbon.device.application.mgt.core/src/main/java/org/wso2/carbon/device/application/mgt/core/impl/ApplicationManagerImpl.java

@@ -66,8 +66,6 @@ import java.util.Date;
 public class ApplicationManagerImpl implements ApplicationManager {
 
     private static final Log log = LogFactory.getLog(ApplicationManagerImpl.class);
-    private static final int DEFAULT_LIMIT = 20;
-    private static final int DEFAULT_OFFSET = 10;
     private DeviceTypeDAO deviceTypeDAO;
     private VisibilityDAO visibilityDAO;
     private ApplicationDAO applicationDAO;
@@ -843,12 +841,6 @@ public class ApplicationManagerImpl implements ApplicationManager {
 
     private Filter validateFilter(Filter filter) {
         if (filter != null) {
-            if (filter.getLimit() == 0) {
-                filter.setLimit(DEFAULT_LIMIT);
-            }
-            if (filter.getOffset() == 0) {
-                filter.setOffset(DEFAULT_OFFSET);
-            }
             if (!SortingOrder.ASC.toString().equals(filter.getSortBy()) &&
                     !SortingOrder.DESC.toString().equals(filter.getSortBy())) {
                 return null;

components/application-mgt/org.wso2.carbon.device.application.mgt.publisher.api/src/main/java/org/wso2/carbon/device/application/mgt/publisher/api/services/ApplicationManagementAPI.java

@@ -133,9 +133,9 @@ public interface ApplicationManagementAPI {
                             message = "OK. \n Successfully got application list.",
                             response = ApplicationList.class),
                     @ApiResponse(
-                            code = 304,
-                            message = "Not Modified. Empty body because the client already has the latest version "
-                                    + "of the requested resource."),
+                            code = 404,
+                            message = "Not Found. There doesn't have an application which is matched with requested " +
+                                    "query."),
                     @ApiResponse(
                             code = 500,
                             message = "Internal Server Error. \n Error occurred while getting the application list.",
@@ -146,7 +146,17 @@ public interface ApplicationManagementAPI {
                     name = "filter",
                     value = "Filter to get application list",
                     required = true)
-            @Valid Filter filter
+            @Valid Filter filter,
+            @ApiParam(
+                    name = "offset",
+                    value = "offset",
+                    defaultValue = "0")
+            @QueryParam("offset") int offset,
+            @ApiParam(
+                    name = "limit",
+                    value = "limit",
+                    defaultValue = "20")
+            @QueryParam("limit") int limit
     );
 
     @GET

components/application-mgt/org.wso2.carbon.device.application.mgt.publisher.api/src/main/java/org/wso2/carbon/device/application/mgt/publisher/api/services/impl/ApplicationManagementAPIImpl.java

@@ -61,10 +61,15 @@ public class ApplicationManagementAPIImpl implements ApplicationManagementAPI {
     @GET
     @Override
     @Consumes("application/json")
-    public Response getApplications(@Valid Filter filter) {
+    public Response getApplications(
+            @Valid Filter filter,
+            @QueryParam("offset") int offset,
+            @QueryParam("limit") int limit) {
         ApplicationManager applicationManager = APIUtil.getApplicationManager();
 
         try {
+            filter.setOffset(offset);
+            filter.setLimit(limit);
             ApplicationList applications = applicationManager.getApplications(filter);
             if (applications.getApplications().isEmpty()) {
                 return Response.status(Response.Status.NOT_FOUND).entity