ONOS-3378 REST DELETE operation on network config subject class key

- delete operation was not working because the incorrect class was being passed
  to the lookup method.
- changed delete operations to return status 204 in lieu of 200 since
  no actual content is returned.

Change-Id: Ibb5294a7b40996fad5d8a4ede48b0f2b7eb923e1

@@ -254,17 +254,15 @@ public class NetworkConfigWebResource extends AbstractWebResource {
      * Clear all network configurations for a subject class.
      *
      * @param subjectClassKey subject class key
-     * @return empty response
      */
     @DELETE
     @Path("{subjectClassKey}")
     @SuppressWarnings("unchecked")
-    public Response delete(@PathParam("subjectClassKey") String subjectClassKey) {
+    public void delete(@PathParam("subjectClassKey") String subjectClassKey) {
         NetworkConfigService service = get(NetworkConfigService.class);
-        service.getSubjects(service.getSubjectFactory(subjectClassKey).getClass())
+        service.getSubjects(service.getSubjectFactory(subjectClassKey).subjectClass())
                 .forEach(subject -> service.getConfigs(subject)
                         .forEach(config -> service.removeConfig(subject, config.getClass())));
-        return Response.ok().build();
     }
 
     /**
@@ -272,17 +270,15 @@ public class NetworkConfigWebResource extends AbstractWebResource {
      *
      * @param subjectClassKey subjectKey class key
      * @param subjectKey      subjectKey key
-     * @return empty response
      */
     @DELETE
     @Path("{subjectClassKey}/{subjectKey}")
     @SuppressWarnings("unchecked")
-    public Response delete(@PathParam("subjectClassKey") String subjectClassKey,
+    public void delete(@PathParam("subjectClassKey") String subjectClassKey,
                            @PathParam("subjectKey") String subjectKey) {
         NetworkConfigService service = get(NetworkConfigService.class);
         Object s = service.getSubjectFactory(subjectClassKey).createSubject(subjectKey);
         service.getConfigs(s).forEach(c -> service.removeConfig(s, c.getClass()));
-        return Response.ok().build();
     }
 
     /**
@@ -291,18 +287,16 @@ public class NetworkConfigWebResource extends AbstractWebResource {
      * @param subjectClassKey subjectKey class key
      * @param subjectKey      subjectKey key
      * @param configKey       configuration class key
-     * @return empty response
      */
     @DELETE
     @Path("{subjectClassKey}/{subjectKey}/{configKey}")
     @SuppressWarnings("unchecked")
-    public Response delete(@PathParam("subjectClassKey") String subjectClassKey,
+    public void delete(@PathParam("subjectClassKey") String subjectClassKey,
                            @PathParam("subjectKey") String subjectKey,
                            @PathParam("configKey") String configKey) {
         NetworkConfigService service = get(NetworkConfigService.class);
         service.removeConfig(service.getSubjectFactory(subjectClassKey).createSubject(subjectKey),
                              service.getConfigClass(subjectClassKey, configKey));
-        return Response.ok().build();
     }
 
 }