Make use of Optional more idiomatic

Change-Id: I42b3261169e7cb8408f46c5831f72115f77fd779
diff --git a/drivers/default/src/main/java/org/onosproject/driver/pipeline/OpenstackPipeline.java b/drivers/default/src/main/java/org/onosproject/driver/pipeline/OpenstackPipeline.java
index 7b1a156..a8b3861 100644
--- a/drivers/default/src/main/java/org/onosproject/driver/pipeline/OpenstackPipeline.java
+++ b/drivers/default/src/main/java/org/onosproject/driver/pipeline/OpenstackPipeline.java
@@ -273,15 +273,11 @@
 
 
     private void pass(Objective obj) {
-        if (obj.context().isPresent()) {
-            obj.context().get().onSuccess(obj);
-        }
+        obj.context().ifPresent(context -> context.onSuccess(obj));
     }
 
     private void fail(Objective obj, ObjectiveError error) {
-        if (obj.context().isPresent()) {
-            obj.context().get().onError(obj, error);
-        }
+        obj.context().ifPresent(context -> context.onError(obj, error));
     }
 }