diff --git a/nitrite-mvstore-adapter/src/test/java/org/dizitart/no2/integration/repository/RepositoryFactoryTest.java b/nitrite-mvstore-adapter/src/test/java/org/dizitart/no2/integration/repository/RepositoryFactoryTest.java
index 69ff5238..56ab5ae8 100644
--- a/nitrite-mvstore-adapter/src/test/java/org/dizitart/no2/integration/repository/RepositoryFactoryTest.java
+++ b/nitrite-mvstore-adapter/src/test/java/org/dizitart/no2/integration/repository/RepositoryFactoryTest.java
@@ -228,7 +228,7 @@ public String subscribe(CollectionEventListener listener) {
 
         @Override
         public void unsubscribe(String subscription) {
-
+            // do nothing
         }
 
         @Override
diff --git a/nitrite-rocksdb-adapter/src/test/java/org/dizitart/no2/integration/repository/RepositoryFactoryTest.java b/nitrite-rocksdb-adapter/src/test/java/org/dizitart/no2/integration/repository/RepositoryFactoryTest.java
index 6d80664b..dde75dc4 100644
--- a/nitrite-rocksdb-adapter/src/test/java/org/dizitart/no2/integration/repository/RepositoryFactoryTest.java
+++ b/nitrite-rocksdb-adapter/src/test/java/org/dizitart/no2/integration/repository/RepositoryFactoryTest.java
@@ -228,7 +228,7 @@ public String subscribe(CollectionEventListener listener) {
 
         @Override
         public void unsubscribe(String subscription) {
-
+            // do nothing
         }
 
         @Override
diff --git a/nitrite/src/test/java/org/dizitart/no2/collection/events/EventAwareTest.java b/nitrite/src/test/java/org/dizitart/no2/collection/events/EventAwareTest.java
index d94660f9..f32b06b2 100644
--- a/nitrite/src/test/java/org/dizitart/no2/collection/events/EventAwareTest.java
+++ b/nitrite/src/test/java/org/dizitart/no2/collection/events/EventAwareTest.java
@@ -16,7 +16,7 @@ public String subscribe(CollectionEventListener listener) {
 
             @Override
             public void unsubscribe(String listener) {
-
+                // do nothing
             }
         };
         eventAware.subscribe(null);
diff --git a/nitrite/src/test/java/org/dizitart/no2/integration/repository/RepositoryFactoryTest.java b/nitrite/src/test/java/org/dizitart/no2/integration/repository/RepositoryFactoryTest.java
index 2d584951..f85c5707 100644
--- a/nitrite/src/test/java/org/dizitart/no2/integration/repository/RepositoryFactoryTest.java
+++ b/nitrite/src/test/java/org/dizitart/no2/integration/repository/RepositoryFactoryTest.java
@@ -221,7 +221,7 @@ public String subscribe(CollectionEventListener listener) {
 
         @Override
         public void unsubscribe(String subscription) {
-
+            // do nothing
         }
 
         @Override