Code cleanup (#1461)

* Code cleanup

* Fix flux tests

* Fix checkstyle errors

* Fix compile error

sharding/src/main/java/com/iluwatar/sharding/LookupShardManager.java

@@ -39,7 +39,7 @@ public class LookupShardManager extends ShardManager {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(LookupShardManager.class);
 
-  private Map<Integer, Integer> lookupMap = new HashMap<>();
+  private final Map<Integer, Integer> lookupMap = new HashMap<>();
 
   @Override
   public int storeData(Data data) {

sharding/src/main/java/com/iluwatar/sharding/Shard.java

@@ -33,7 +33,7 @@ public class Shard {
 
   private final int id;
 
-  private Map<Integer, Data> dataStore;
+  private final Map<Integer, Data> dataStore;
 
   public Shard(final int id) {
     this.id = id;