Allow NextObjective to refer to another NextObjective by NextId

Change-Id: I4bc5381be8241ddd765668275f02f795ba06a632
(cherry picked from commit 7fbd2b167ac2a8981255dc17aa53b2ba93073018)
(cherry picked from commit f261d5cbaf8e936b5e3b2f0c55d8e9e698922d2d)
diff --git a/core/api/src/main/java/org/onosproject/net/flowobjective/DefaultNextObjective.java b/core/api/src/main/java/org/onosproject/net/flowobjective/DefaultNextObjective.java
index 8c466c9..36656c4 100644
--- a/core/api/src/main/java/org/onosproject/net/flowobjective/DefaultNextObjective.java
+++ b/core/api/src/main/java/org/onosproject/net/flowobjective/DefaultNextObjective.java
@@ -25,6 +25,7 @@
 import java.util.List;
 import java.util.Objects;
 import java.util.Optional;
+import java.util.stream.Collectors;
 
 import static com.google.common.base.MoreObjects.toStringHelper;
 import static com.google.common.base.Preconditions.checkArgument;
@@ -36,7 +37,7 @@
 @Beta
 public final class DefaultNextObjective implements NextObjective {
 
-    private final List<TrafficTreatment> treatments;
+    private final List<NextTreatment> treatments;
     private final ApplicationId appId;
     private final Type type;
     private final Integer id;
@@ -56,6 +57,14 @@
 
     @Override
     public Collection<TrafficTreatment> next() {
+        return treatments.stream()
+                .filter(t -> t.type() == NextTreatment.Type.TREATMENT)
+                .map(t -> ((DefaultNextTreatment) t).treatment())
+                .collect(Collectors.toList());
+    }
+
+    @Override
+    public Collection<NextTreatment> nextTreatments() {
         return treatments;
     }
 
@@ -133,7 +142,7 @@
                 .add("type", type())
                 .add("op", op())
                 .add("priority", priority())
-                .add("next", next())
+                .add("nextTreatments", nextTreatments())
                 .add("meta", meta())
                 .add("appId", appId())
                 .add("permanent", permanent())
@@ -160,12 +169,12 @@
         private ApplicationId appId;
         private Type type;
         private Integer id;
-        private List<TrafficTreatment> treatments;
+        private List<NextTreatment> treatments;
         private Operation op;
         private ObjectiveContext context;
         private TrafficSelector meta;
 
-        private final ImmutableList.Builder<TrafficTreatment> listBuilder
+        private final ImmutableList.Builder<NextTreatment> listBuilder
                 = ImmutableList.builder();
 
         // Creates an empty builder
@@ -176,8 +185,8 @@
         private Builder(NextObjective objective) {
             this.type = objective.type();
             this.id = objective.id();
-            this.treatments = ImmutableList.copyOf(objective.next());
-            this.listBuilder.addAll(objective.next());
+            this.treatments = ImmutableList.copyOf(objective.nextTreatments());
+            this.listBuilder.addAll(objective.nextTreatments());
             this.meta = objective.meta();
             this.appId = objective.appId();
             this.op = objective.op();
@@ -197,7 +206,13 @@
 
         @Override
         public Builder addTreatment(TrafficTreatment treatment) {
-            listBuilder.add(treatment);
+            listBuilder.add(DefaultNextTreatment.of(treatment));
+            return this;
+        }
+
+        @Override
+        public Builder addTreatment(NextTreatment nextTreatment) {
+            listBuilder.add(nextTreatment);
             return this;
         }