diff --git a/azure-client-runtime/src/main/java/com/microsoft/azure/PagedList.java b/azure-client-runtime/src/main/java/com/microsoft/azure/PagedList.java
index 4f966acbcf3d..8db10337d989 100644
--- a/azure-client-runtime/src/main/java/com/microsoft/azure/PagedList.java
+++ b/azure-client-runtime/src/main/java/com/microsoft/azure/PagedList.java
@@ -47,7 +47,10 @@ public PagedList() {
      */
     public PagedList(Page<E> page) {
         this();
-        items.addAll(page.getItems());
+        List<E> retrievedItems = page.getItems();
+        if (retrievedItems != null && retrievedItems.size() != 0) {
+            items.addAll(retrievedItems);
+        }
         nextPageLink = page.getNextPageLink();
         currentPage = page;
     }
@@ -138,14 +141,17 @@ public boolean hasNext() {
         public E next() {
             if (!itemsListItr.hasNext()) {
                 if (!hasNextPage()) {
-                    throw new NoSuchElementException();
+                    throw new NoSuchElementException();                        
                 } else {
                     int size = items.size();
                     loadNextPage();
                     itemsListItr = items.listIterator(size);
                 }
             }
-            return itemsListItr.next();
+            if (itemsListItr.hasNext()) {
+                return itemsListItr.next();
+            }
+            return null;
         }
 
         @Override
diff --git a/azure-client-runtime/src/main/java/com/microsoft/azure/TaskGroup.java b/azure-client-runtime/src/main/java/com/microsoft/azure/TaskGroup.java
index 75722a494fea..ada803b38c3e 100644
--- a/azure-client-runtime/src/main/java/com/microsoft/azure/TaskGroup.java
+++ b/azure-client-runtime/src/main/java/com/microsoft/azure/TaskGroup.java
@@ -47,15 +47,6 @@ public interface TaskGroup<T, U extends TaskItem<T>> {
      */
     void prepare();
 
-    /**
-     * Executes the tasks in the group.
-     * <p>
-     * the order of execution of tasks ensure that a task gets selected for execution only after
-     * the execution of all the tasks it depends on
-     * @throws Exception the exception
-     */
-    void execute() throws Exception;
-
     /**
      * Executes the tasks in the group asynchronously.
      *
diff --git a/azure-client-runtime/src/main/java/com/microsoft/azure/TaskGroupBase.java b/azure-client-runtime/src/main/java/com/microsoft/azure/TaskGroupBase.java
index 46fe8d0f179f..747f0273fa7d 100644
--- a/azure-client-runtime/src/main/java/com/microsoft/azure/TaskGroupBase.java
+++ b/azure-client-runtime/src/main/java/com/microsoft/azure/TaskGroupBase.java
@@ -58,31 +58,8 @@ public void prepare() {
         }
     }
 
-    @Override
-    public void execute() throws Exception {
-        DAGNode<U> nextNode = dag.getNext();
-        while (nextNode != null) {
-            nextNode.data().execute();
-            this.dag().reportedCompleted(nextNode);
-            nextNode = dag.getNext();
-        }
-    }
-
     @Override
     public Observable<T> executeAsync() {
-        return executeReadyTasksAsync().last();
-    }
-
-    @Override
-    public T taskResult(String taskId) {
-        return dag.getNodeData(taskId).result();
-    }
-
-    /**
-     * Executes all runnable tasks, a task is runnable when all the tasks its depends
-     * on are finished running.
-     */
-    private Observable<T> executeReadyTasksAsync() {
         DAGNode<U> nextNode = dag.getNext();
         final List<Observable<T>> observables = new ArrayList<>();
         while (nextNode != null) {
@@ -95,7 +72,7 @@ public Observable<T> call(T t) {
                             if (dag().isRootNode(thisNode)) {
                                 return Observable.just(t);
                             } else {
-                                return executeReadyTasksAsync();
+                                return executeAsync();
                             }
                         }
                     }));
@@ -103,4 +80,9 @@ public Observable<T> call(T t) {
         }
         return Observable.merge(observables);
     }
+
+    @Override
+    public T taskResult(String taskId) {
+        return dag.getNodeData(taskId).result();
+    }
 }
diff --git a/azure-client-runtime/src/main/java/com/microsoft/azure/TaskItem.java b/azure-client-runtime/src/main/java/com/microsoft/azure/TaskItem.java
index df9bf4b04a94..dd24167c8968 100644
--- a/azure-client-runtime/src/main/java/com/microsoft/azure/TaskItem.java
+++ b/azure-client-runtime/src/main/java/com/microsoft/azure/TaskItem.java
@@ -20,15 +20,6 @@ public interface TaskItem<U> {
      */
     U result();
 
-    /**
-     * Executes the task.
-     * <p>
-     * once executed the result will be available through result getter
-     *
-     * @throws Exception exception
-     */
-    void execute() throws Exception;
-
     /**
      * Executes the task asynchronously.
      * <p>