Make all leaf intent classes immutable

Change-Id: I45a9ac42a401b707c0c0d91f2e55294f3571ca25
diff --git a/core/api/src/main/java/org/onosproject/net/intent/OpticalPathIntent.java b/core/api/src/main/java/org/onosproject/net/intent/OpticalPathIntent.java
index 123876b..6804c86 100644
--- a/core/api/src/main/java/org/onosproject/net/intent/OpticalPathIntent.java
+++ b/core/api/src/main/java/org/onosproject/net/intent/OpticalPathIntent.java
@@ -24,7 +24,7 @@
 
 import java.util.Collection;
 
-public class OpticalPathIntent extends Intent {
+public final class OpticalPathIntent extends Intent {
 
     private final ConnectPoint src;
     private final ConnectPoint dst;