switched to resource-types for annotations to get around circular dependency issues

src/app/core/tasks/models/task-object.model.ts

@@ -34,19 +34,19 @@ export class TaskObject extends DSpaceObject implements CacheableObject {
   /**
    * The group of this task
    */
-  @link(EPerson)
+  @link(EPerson.type)
   eperson?: Observable<RemoteData<EPerson>>;
 
   /**
    * The group of this task
    */
-  @link(Group)
+  @link(Group.type)
   group?: Observable<RemoteData<Group>>;
 
   /**
    * The workflowitem object whom this task is related
    */
-  @link(WorkflowItem)
+  @link(WorkflowItem.type)
   workflowitem?: Observable<RemoteData<WorkflowItem>> | WorkflowItem;
 
   _links: {