[ONOS-7068] Upgrade to Atomix 2.0.4

Change-Id: I864567084b1ac230254533026f06d4a25e5e0a2d
diff --git a/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/StorageNamespaces.java b/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/StorageNamespaces.java
index 0333b00..8350499 100644
--- a/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/StorageNamespaces.java
+++ b/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/StorageNamespaces.java
@@ -39,6 +39,8 @@
 import io.atomix.protocols.raft.protocol.CommandResponse;
 import io.atomix.protocols.raft.protocol.ConfigureRequest;
 import io.atomix.protocols.raft.protocol.ConfigureResponse;
+import io.atomix.protocols.raft.protocol.HeartbeatRequest;
+import io.atomix.protocols.raft.protocol.HeartbeatResponse;
 import io.atomix.protocols.raft.protocol.InstallRequest;
 import io.atomix.protocols.raft.protocol.InstallResponse;
 import io.atomix.protocols.raft.protocol.JoinRequest;
@@ -106,6 +108,8 @@
             .register(CloseSessionResponse.class)
             .register(KeepAliveRequest.class)
             .register(KeepAliveResponse.class)
+            .register(HeartbeatRequest.class)
+            .register(HeartbeatResponse.class)
             .register(QueryRequest.class)
             .register(QueryResponse.class)
             .register(CommandRequest.class)