diff --git a/src/main/java/de/shahondin1624/knowledgegraph/util/DbHelper.java b/src/main/java/de/shahondin1624/knowledgegraph/util/DbHelper.java
index ad6c2cf..56e3ca6 100644
--- a/src/main/java/de/shahondin1624/knowledgegraph/util/DbHelper.java
+++ b/src/main/java/de/shahondin1624/knowledgegraph/util/DbHelper.java
@@ -10,7 +10,7 @@ public class DbHelper {
     private static final Logger logger = LoggerFactory.getLogger(DbHelper.class);
     private final GraphDatabaseService graphDb;
 
-    public DbHelper(GraphDatabaseService graphDb) {
+    public DbHelper(final GraphDatabaseService graphDb) {
         this.graphDb = graphDb;
     }
 
@@ -19,7 +19,7 @@ public class DbHelper {
     }
 
     @SuppressWarnings("unchecked")
-    public <E, T extends Throwable> Result<E, T> wrapInTx(TransactionContextWithReturn<E> action) {
+    public <E, T extends Throwable> Result<E, T> wrapInTx(final TransactionContextWithReturn<E> action) {
         try (final TransactionWrapper tx = new TransactionWrapper(beginTx())) {
             final E result = action.execute(tx);
             tx.commit();
@@ -31,7 +31,7 @@ public class DbHelper {
     }
 
     @SuppressWarnings("unchecked")
-    public <T extends Throwable> Result<Void, T> wrapInTx(TransactionContextWithoutReturn action) {
+    public <T extends Throwable> Result<Void, T> wrapInTx(final TransactionContextWithoutReturn action) {
         try (final TransactionWrapper tx = new TransactionWrapper(beginTx())) {
             action.execute(tx);
             tx.commit();