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 8f178480c43b..e53bfa0a0196 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
@@ -21,7 +21,14 @@
  */
 public abstract class TaskGroupBase<T, U extends TaskItem<T>>
     implements TaskGroup<T, U> {
+    /**
+     * Stores the tasks in this group and their dependency information.
+     */
     private DAGraph<U, DAGNode<U>> dag;
+    /**
+     * ServiceCall instance that aggregate a set of ServiceCalls each associated with
+     * the task in this group.
+     */
     private ParallelServiceCall parallelServiceCall;
 
     /**
@@ -87,7 +94,7 @@ public T taskResult(String taskId) {
     private void executeReadyTasksAsync(final ServiceCallback<T> callback) {
         DAGNode<U> nextNode = dag.getNext();
         while (nextNode != null) {
-            ServiceCall serviceCall = nextNode.data().executeAsync(taskCallback(nextNode, callback));
+            ServiceCall<T> serviceCall = nextNode.data().executeAsync(taskCallback(nextNode, callback));
             this.parallelServiceCall.addCall(serviceCall);
             nextNode = dag.getNext();
         }
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 8f0a3459a2e9..1a4bd9a61bf4 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
@@ -38,5 +38,5 @@ public interface TaskItem<U> {
      * @param callback callback to call on success or failure
      * @return the handle of the REST call
      */
-    ServiceCall executeAsync(ServiceCallback<U> callback);
+    ServiceCall<U> executeAsync(ServiceCallback<U> callback);
 }