Explicitly return NO CONTENT type response for http DELETE request

Change-Id: I920084b92197bb1687e7d978ad350b2e1290ecbc
diff --git a/apps/vtn/vtnweb/src/main/java/org/onosproject/vtnweb/resources/VirtualPortWebResource.java b/apps/vtn/vtnweb/src/main/java/org/onosproject/vtnweb/resources/VirtualPortWebResource.java
index f99192c..a635c11 100644
--- a/apps/vtn/vtnweb/src/main/java/org/onosproject/vtnweb/resources/VirtualPortWebResource.java
+++ b/apps/vtn/vtnweb/src/main/java/org/onosproject/vtnweb/resources/VirtualPortWebResource.java
@@ -15,32 +15,11 @@
  */
 package org.onosproject.vtnweb.resources;
 
-import static com.google.common.base.Preconditions.checkArgument;
-import static com.google.common.base.Preconditions.checkNotNull;
-import static javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR;
-import static javax.ws.rs.core.Response.Status.OK;
-import static javax.ws.rs.core.Response.Status.NOT_FOUND;
-
-import java.io.InputStream;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.Map;
-import java.util.Set;
-import java.util.concurrent.ConcurrentMap;
-
-import javax.ws.rs.Consumes;
-import javax.ws.rs.DELETE;
-import javax.ws.rs.GET;
-import javax.ws.rs.POST;
-import javax.ws.rs.PUT;
-import javax.ws.rs.Path;
-import javax.ws.rs.PathParam;
-import javax.ws.rs.Produces;
-import javax.ws.rs.core.MediaType;
-import javax.ws.rs.core.Response;
-
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.google.common.collect.Maps;
+import com.google.common.collect.Sets;
 import org.onlab.packet.IpAddress;
 import org.onlab.packet.MacAddress;
 import org.onlab.util.ItemNotFoundException;
@@ -62,11 +41,30 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import com.fasterxml.jackson.databind.JsonNode;
-import com.fasterxml.jackson.databind.ObjectMapper;
-import com.fasterxml.jackson.databind.node.ObjectNode;
-import com.google.common.collect.Maps;
-import com.google.common.collect.Sets;
+import javax.ws.rs.Consumes;
+import javax.ws.rs.DELETE;
+import javax.ws.rs.GET;
+import javax.ws.rs.POST;
+import javax.ws.rs.PUT;
+import javax.ws.rs.Path;
+import javax.ws.rs.PathParam;
+import javax.ws.rs.Produces;
+import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.Response;
+import java.io.InputStream;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentMap;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkNotNull;
+import static javax.ws.rs.core.Response.Status.INTERNAL_SERVER_ERROR;
+import static javax.ws.rs.core.Response.Status.NOT_FOUND;
+import static javax.ws.rs.core.Response.Status.OK;
 
 /**
  * REST resource for interacting with the inventory of infrastructure
@@ -146,7 +144,7 @@
                 return Response.status(INTERNAL_SERVER_ERROR)
                         .entity(VPORT_ID_NOT_EXIST).build();
             }
-            return Response.status(OK).entity(issuccess.toString()).build();
+            return ok(issuccess.toString()).build();
         } catch (Exception e) {
             log.error("Deletes VirtualPort failed because of exception {}",
                       e.toString());