Fix for ONOS-5566:Issue With Region POST-DELETE REST API:Incorporated Comments

Change-Id: Id14480f26e02b87fab3e3c6a0b9f111d9477c3ac
diff --git a/web/api/src/main/java/org/onosproject/rest/resources/RegionsWebResource.java b/web/api/src/main/java/org/onosproject/rest/resources/RegionsWebResource.java
index c17683c..cc6444a 100644
--- a/web/api/src/main/java/org/onosproject/rest/resources/RegionsWebResource.java
+++ b/web/api/src/main/java/org/onosproject/rest/resources/RegionsWebResource.java
@@ -193,11 +193,13 @@
     @Produces(MediaType.APPLICATION_JSON)
     public Response addDevices(@PathParam("regionId") String regionId,
                                InputStream stream) {
-        final RegionId rid = RegionId.regionId(regionId);
+        RegionId rid = RegionId.regionId(regionId);
+        Region region = nullIsNotFound(regionService.getRegion(rid),
+                REGION_NOT_FOUND + rid);
 
         URI location;
         try {
-            regionAdminService.addDevices(rid, extractDeviceIds(stream));
+            regionAdminService.addDevices(region.id(), extractDeviceIds(stream));
             location = new URI(rid.id());
         } catch (IOException | URISyntaxException e) {
             throw new IllegalArgumentException(e);
@@ -219,7 +221,9 @@
     @Consumes(MediaType.APPLICATION_JSON)
     public Response removeDevices(@PathParam("regionId") String regionId,
                                   InputStream stream) {
-        final RegionId rid = RegionId.regionId(regionId);
+        RegionId rid = RegionId.regionId(regionId);
+        Region region = nullIsNotFound(regionService.getRegion(rid),
+                REGION_NOT_FOUND + rid);
 
         try {
             regionAdminService.removeDevices(rid, extractDeviceIds(stream));