diff --git a/hawkbit-rest/hawkbit-ddi-api/src/test/java/org/eclipse/hawkbit/ddi/json/model/DdiConfirmationBaseTest.java b/hawkbit-rest/hawkbit-ddi-api/src/test/java/org/eclipse/hawkbit/ddi/json/model/DdiConfirmationBaseTest.java
index b76fe810b..1ce740a88 100644
--- a/hawkbit-rest/hawkbit-ddi-api/src/test/java/org/eclipse/hawkbit/ddi/json/model/DdiConfirmationBaseTest.java
+++ b/hawkbit-rest/hawkbit-ddi-api/src/test/java/org/eclipse/hawkbit/ddi/json/model/DdiConfirmationBaseTest.java
@@ -34,7 +34,7 @@ import org.junit.jupiter.api.Test;
 @Story("CHeck JSON serialization of DDI api confirmation models")
 class DdiConfirmationBaseTest {
 
-    private final ObjectMapper mapper = new ObjectMapper();
+    private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
 
     @Test
     @Description("Verify the correct serialization and deserialization of the model")
@@ -49,8 +49,8 @@ class DdiConfirmationBaseTest {
                 ddiActionHistory);
 
         // Test
-        String serializedDdiConfirmationBase = mapper.writeValueAsString(ddiConfirmationBaseAction);
-        final DdiConfirmationBaseAction deserializedDdiConfigurationBase = mapper
+        String serializedDdiConfirmationBase = OBJECT_MAPPER.writeValueAsString(ddiConfirmationBaseAction);
+        final DdiConfirmationBaseAction deserializedDdiConfigurationBase = OBJECT_MAPPER
                 .readValue(serializedDdiConfirmationBase, DdiConfirmationBaseAction.class);
 
         assertThat(serializedDdiConfirmationBase).contains(id, FORCED.getName(), ATTEMPT.getName(),
@@ -68,13 +68,15 @@ class DdiConfirmationBaseTest {
     @Description("Verify the correct deserialization of a model with a additional unknown property")
     void shouldDeserializeObjectWithUnknownProperty() throws IOException {
         // Setup
-        String serializedDdiConfirmationBase = "{\"id\":\"1234\",\"confirmation\":{\"download\":\"forced\","
-                + "\"update\":\"attempt\",\"maintenanceWindow\":\"available\",\"chunks\":[]},"
-                + "\"actionHistory\":{\"status\":\"TestAction\",\"messages\":[\"Action status message 1\","
-                + "\"Action status message 2\"]},\"links\":[],\"unknownProperty\":\"test\"}";
+        final String serializedDdiConfirmationBase = "{" +
+                "\"id\":\"1234\",\"confirmation\":{\"download\":\"forced\"," +
+                "\"update\":\"attempt\",\"maintenanceWindow\":\"available\",\"chunks\":[]}," +
+                "\"actionHistory\":{\"status\":\"TestAction\",\"messages\":[\"Action status message 1\"," +
+                "\"Action status message 2\"]},\"links\":[],\"unknownProperty\":\"test\"" +
+                "}";
 
         // Test
-        DdiConfirmationBaseAction ddiConfirmationBaseAction = mapper.readValue(serializedDdiConfirmationBase,
+        final DdiConfirmationBaseAction ddiConfirmationBaseAction = OBJECT_MAPPER.readValue(serializedDdiConfirmationBase,
                 DdiConfirmationBaseAction.class);
 
         assertThat(ddiConfirmationBaseAction.getConfirmation().getDownload().getName()).isEqualTo(FORCED.getName());
@@ -87,13 +89,15 @@ class DdiConfirmationBaseTest {
     @Description("Verify that deserialization fails for known properties with a wrong datatype")
     void shouldFailForObjectWithWrongDataTypes() throws IOException {
         // Setup
-        String serializedDdiConfirmationBase = "{\"id\":[\"1234\"],\"confirmation\":{\"download\":\"forced\","
-                + "\"update\":\"attempt\",\"maintenanceWindow\":\"available\",\"chunks\":[]},"
-                + "\"actionHistory\":{\"status\":\"TestAction\",\"messages\":[\"Action status message 1\","
-                + "\"Action status message 2\"]},\"links\":[]}";
+        final String serializedDdiConfirmationBase = "{" +
+                "\"id\":[\"1234\"],\"confirmation\":{\"download\":\"forced\"," +
+                "\"update\":\"attempt\",\"maintenanceWindow\":\"available\",\"chunks\":[]}," +
+                "\"actionHistory\":{\"status\":\"TestAction\",\"messages\":[\"Action status message 1\"," +
+                "\"Action status message 2\"]},\"links\":[]" +
+                "}";
 
         // Test
         assertThatExceptionOfType(MismatchedInputException.class)
-                .isThrownBy(() -> mapper.readValue(serializedDdiConfirmationBase, DdiConfirmationBaseAction.class));
+                .isThrownBy(() -> OBJECT_MAPPER.readValue(serializedDdiConfirmationBase, DdiConfirmationBaseAction.class));
     }
 }
\ No newline at end of file
diff --git a/hawkbit-rest/hawkbit-ddi-resource/src/test/java/org/eclipse/hawkbit/ddi/rest/resource/DdiConfirmationBaseTest.java b/hawkbit-rest/hawkbit-ddi-resource/src/test/java/org/eclipse/hawkbit/ddi/rest/resource/DdiConfirmationBaseTest.java
index bc410d438..17c377211 100644
--- a/hawkbit-rest/hawkbit-ddi-resource/src/test/java/org/eclipse/hawkbit/ddi/rest/resource/DdiConfirmationBaseTest.java
+++ b/hawkbit-rest/hawkbit-ddi-resource/src/test/java/org/eclipse/hawkbit/ddi/rest/resource/DdiConfirmationBaseTest.java
@@ -69,14 +69,13 @@ import org.springframework.test.web.servlet.ResultActions;
  */
 @Feature("Component Tests - Direct Device Integration API")
 @Story("Confirmation Action Resource")
-public class DdiConfirmationBaseTest extends AbstractDDiApiIntegrationTest {
+class DdiConfirmationBaseTest extends AbstractDDiApiIntegrationTest {
 
     private static final String DEFAULT_CONTROLLER_ID = "4747";
 
     @Test
-    @Description("Forced deployment to a controller. Checks if the confirmation resource response payload for a given"
-            + " deployment is as expected.")
-    public void verifyConfirmationReferencesInControllerBase(@Autowired ActionStatusRepository actionStatusRepository) throws Exception {
+    @Description("Forced deployment to a controller. Checks if the confirmation resource response payload for a given deployment is as expected.")
+    void verifyConfirmationReferencesInControllerBase(@Autowired ActionStatusRepository actionStatusRepository) throws Exception {
         enableConfirmationFlow();
         // Prepare test data
         final DistributionSet ds = testdataFactory.createDistributionSet("", true);
@@ -142,7 +141,7 @@ public class DdiConfirmationBaseTest extends AbstractDDiApiIntegrationTest {
 
     @Test
     @Description("Ensure that the deployment resource is available as CBOR")
-    public void confirmationResourceCbor() throws Exception {
+    void confirmationResourceCbor() throws Exception {
         enableConfirmationFlow();
         final Target target = testdataFactory.createTarget();
         final DistributionSet distributionSet = testdataFactory.createDistributionSet("");
@@ -156,19 +155,23 @@ public class DdiConfirmationBaseTest extends AbstractDDiApiIntegrationTest {
                 .getContent().get(0);
 
         // get confirmation base
-        performGet(CONFIRMATION_BASE_ACTION, MediaType.parseMediaType(DdiRestConstants.MEDIA_TYPE_CBOR),
-                status().isOk(), tenantAware.getCurrentTenant(), target.getControllerId(), action.getId().toString());
+        assertThat(
+                performGet(
+                        CONFIRMATION_BASE_ACTION, MediaType.parseMediaType(DdiRestConstants.MEDIA_TYPE_CBOR),
+                        status().isOk(), tenantAware.getCurrentTenant(), target.getControllerId(), action.getId().toString()))
+                .isNotNull();
 
         // get artifacts
-        performGet(SOFTWARE_MODULE_ARTIFACTS, MediaType.parseMediaType(DdiRestConstants.MEDIA_TYPE_CBOR),
-                status().isOk(), tenantAware.getCurrentTenant(), target.getControllerId(),
-                String.valueOf(softwareModuleId));
-
+        assertThat(
+                performGet(SOFTWARE_MODULE_ARTIFACTS, MediaType.parseMediaType(DdiRestConstants.MEDIA_TYPE_CBOR),
+                        status().isOk(), tenantAware.getCurrentTenant(), target.getControllerId(),
+                        String.valueOf(softwareModuleId)))
+                .isNotNull();
     }
 
     @Test
     @Description("Ensure that the confirmation endpoint is not available.")
-    public void confirmationEndpointNotExposed() throws Exception {
+    void confirmationEndpointNotExposed() throws Exception {
         final DistributionSet ds = testdataFactory.createDistributionSet("");
         Target savedTarget = testdataFactory.createTarget("988");
         savedTarget = getFirstAssignedTarget(assignDistributionSet(ds.getId(), savedTarget.getControllerId()));
@@ -190,7 +193,7 @@ public class DdiConfirmationBaseTest extends AbstractDDiApiIntegrationTest {
 
     @Test
     @Description("Ensure that the deploymentBase endpoint is not available for action ins WFC state.")
-    public void deploymentEndpointNotAccessibleForActionsWFC() throws Exception {
+    void deploymentEndpointNotAccessibleForActionsWFC() throws Exception {
         enableConfirmationFlow();
 
         final DistributionSet ds = testdataFactory.createDistributionSet("");
@@ -218,7 +221,7 @@ public class DdiConfirmationBaseTest extends AbstractDDiApiIntegrationTest {
 
     @Test
     @Description("Ensure that the confirmation endpoints are still available after deactivating the confirmation flow.")
-    public void verifyConfirmationBaseEndpointsArePresentAfterDisablingConfirmationFlow() throws Exception {
+    void verifyConfirmationBaseEndpointsArePresentAfterDisablingConfirmationFlow() throws Exception {
         enableConfirmationFlow();
 
         final DistributionSet ds = testdataFactory.createDistributionSet("");