Fixing Protected P2PIntent Compiler issues

- Register ProtectionConstraint
- Workaround for NPE in P2PIntent Compiler
  buildFailoverTreatment sometimes throw NPE,
  when the Group was not available by the time building the head-end treatment.
- debug log and cosmetic fixes

This might be related to ONOS-5183

Change-Id: I5ffc78619951fd8c4a35e985b3b849a1702080e8
diff --git a/core/api/src/main/java/org/onosproject/net/group/DefaultGroupDescription.java b/core/api/src/main/java/org/onosproject/net/group/DefaultGroupDescription.java
index 1962e0a..7ef7dfb 100644
--- a/core/api/src/main/java/org/onosproject/net/group/DefaultGroupDescription.java
+++ b/core/api/src/main/java/org/onosproject/net/group/DefaultGroupDescription.java
@@ -203,6 +203,7 @@
                 .add("type", type)
                 .add("buckets", buckets)
                 .add("appId", appId)
+                .add("appCookie", appCookie)
                 .add("givenGroupId", givenGroupId)
                 .toString();
     }