Simplify lambda expressions by using method reference

Change-Id: I434c0020ce8c2c25ac41d256d5ac141793972970
diff --git a/drivers/default/src/main/java/org/onosproject/driver/pipeline/SpringOpenTTP.java b/drivers/default/src/main/java/org/onosproject/driver/pipeline/SpringOpenTTP.java
index b391606..f0ad4c1 100644
--- a/drivers/default/src/main/java/org/onosproject/driver/pipeline/SpringOpenTTP.java
+++ b/drivers/default/src/main/java/org/onosproject/driver/pipeline/SpringOpenTTP.java
@@ -336,8 +336,7 @@
                     buckets = nextObjective
                             .next()
                             .stream()
-                            .map((treatment) -> DefaultGroupBucket
-                                 .createSelectGroupBucket(treatment))
+                            .map(DefaultGroupBucket::createSelectGroupBucket)
                             .collect(Collectors.toList());
                     if (!buckets.isEmpty()) {
                         final GroupKey key = new DefaultGroupKey(
@@ -361,8 +360,7 @@
                 buckets = nextObjective
                         .next()
                         .stream()
-                        .map((treatment) -> DefaultGroupBucket
-                                .createAllGroupBucket(treatment))
+                        .map(DefaultGroupBucket::createAllGroupBucket)
                         .collect(Collectors.toList());
                 if (!buckets.isEmpty()) {
                     final GroupKey key = new DefaultGroupKey(