[ONOS-6624]Unit tests for Pi* core classes

Change-Id: Ia0a20712f8108549b3ac6434be8aee1bc6025bb2
diff --git a/core/api/src/test/java/org/onosproject/net/flow/criteria/CriteriaTest.java b/core/api/src/test/java/org/onosproject/net/flow/criteria/CriteriaTest.java
index 38c2405..7a89895 100644
--- a/core/api/src/test/java/org/onosproject/net/flow/criteria/CriteriaTest.java
+++ b/core/api/src/test/java/org/onosproject/net/flow/criteria/CriteriaTest.java
@@ -136,7 +136,6 @@
     Criterion sameAsMatchUdpPort1 = Criteria.matchUdpSrc(tpPort1);
     Criterion matchUdpPort2 = Criteria.matchUdpDst(tpPort2);
 
-
     int tcpFlags1 =
         Criterion.TcpFlags.NS.getValue() |
         Criterion.TcpFlags.CWR.getValue() |
@@ -340,6 +339,7 @@
         assertThatClassIsImmutable(OduSignalIdCriterion.class);
         assertThatClassIsImmutable(OduSignalTypeCriterion.class);
         assertThatClassIsImmutable(PbbIsidCriterion.class);
+        assertThatClassIsImmutable(PiCriterion.class);
     }
 
     // PortCriterion class