made MongoDBServiceImpl.configuration volatile to ensure setting it is visible to other threads

Change-Id: I5ed2ac2cf57fed8027a653d32c3e309c5c5a5551

docker/sailing-pod.yaml

@@ -5,7 +5,7 @@ metadata:
 spec:
   containers:
   - name: sailing
-    image: donaldduck70/sapsailing:docker-201812041110
+    image: donaldduck70/sapsailing:docker-201812050126
     imagePullPolicy: Always
     ports:
     - containerPort: 8888

java/com.sap.sse.mongodb/src/com/sap/sse/mongodb/internal/MongoDBServiceImpl.java

@@ -18,7 +18,11 @@ public class MongoDBServiceImpl implements MongoDBService {
 
     private static final Logger logger = Logger.getLogger(MongoDBServiceImpl.class.getName());
 
-    private MongoDBConfiguration configuration;
+    /**
+     * Make this volatile to ensure that when an activator writes it in one thread then another
+     * activator can read it.
+     */
+    private volatile MongoDBConfiguration configuration;
 
     private final Map<MongoClientURI, Mongo> mongos;