Use singleton primitives in transactions

Change-Id: Ibb29a3f10e9863e075a4aba9bc357ed1ca9dfcc1
(cherry picked from commit c1c057aa18b63ceb78f5a95166d8f83bc0967328)
diff --git a/core/store/primitives/src/main/java/org/onosproject/store/atomix/primitives/impl/AtomixTransactionContext.java b/core/store/primitives/src/main/java/org/onosproject/store/atomix/primitives/impl/AtomixTransactionContext.java
index 6be5be0..dd81b09 100644
--- a/core/store/primitives/src/main/java/org/onosproject/store/atomix/primitives/impl/AtomixTransactionContext.java
+++ b/core/store/primitives/src/main/java/org/onosproject/store/atomix/primitives/impl/AtomixTransactionContext.java
@@ -99,6 +99,6 @@
                 .withMaxRetries(MAX_RETRIES)
                 .build())
             .withSerializer(new AtomixSerializerAdapter(serializer))
-            .build());
+            .get());
     }
 }