Add applyAsync()

azure-client-runtime/src/main/java/com/microsoft/azure/TaskItem.java

@@ -27,9 +27,20 @@ public interface TaskItem<U> {
      * once executed the result will be available through result getter
      *
      * @param taskGroup the task group dispatching tasks
+     * @param node the node the task item is associated with
      * @throws Exception exception
      */
     void execute(TaskGroup<U, TaskItem<U>> taskGroup, DAGNode<TaskItem<U>> node) throws Exception;
 
+    /**
+     * Executes the task asynchronously.
+     * <p>
+     * once executed the result will be available through result getter
+
+     * @param taskGroup the task group dispatching tasks
+     * @param node the node the task item is associated with
+     * @param callback callback to call on success or failure
+     * @return the handle of the REST call
+     */
     ServiceCall executeAsync(TaskGroup<U, TaskItem<U>> taskGroup, DAGNode<TaskItem<U>> node, ServiceCallback<Void> callback);
 }