FlowEntry must not be modified outside store.

- Remove set method from FlowEntry
- Storing last seen timestamp for FlowEntry eviction locally on FlowManager.
  FlowEntry eviction based on packet counter will take longer time to timeout
  after master Node change.

Change-Id: I7134d698dd5b9bf7cca379c5ba7c4fbcc2e3d5f3
diff --git a/core/net/src/test/java/org/onlab/onos/net/flow/impl/FlowRuleManagerTest.java b/core/net/src/test/java/org/onlab/onos/net/flow/impl/FlowRuleManagerTest.java
index 472416a..dff740a 100644
--- a/core/net/src/test/java/org/onlab/onos/net/flow/impl/FlowRuleManagerTest.java
+++ b/core/net/src/test/java/org/onlab/onos/net/flow/impl/FlowRuleManagerTest.java
@@ -46,6 +46,7 @@
 import org.onlab.onos.net.flow.FlowRuleProviderRegistry;
 import org.onlab.onos.net.flow.FlowRuleProviderService;
 import org.onlab.onos.net.flow.FlowRuleService;
+import org.onlab.onos.net.flow.StoredFlowEntry;
 import org.onlab.onos.net.flow.TrafficSelector;
 import org.onlab.onos.net.flow.TrafficTreatment;
 import org.onlab.onos.net.flow.criteria.Criterion;
@@ -232,7 +233,7 @@
     public void flowRemoved() {
         FlowRule f1 = addFlowRule(1);
         FlowRule f2 = addFlowRule(2);
-        FlowEntry fe1 = new DefaultFlowEntry(f1);
+        StoredFlowEntry fe1 = new DefaultFlowEntry(f1);
         FlowEntry fe2 = new DefaultFlowEntry(f2);
         providerService.pushFlowMetrics(DID, ImmutableList.of(fe1, fe2));
         service.removeFlowRules(f1);