diff --git a/services/connectivity/messaging/src/main/java/org/eclipse/ditto/services/connectivity/messaging/persistence/ConnectionMongoSnapshotAdapter.java b/services/connectivity/messaging/src/main/java/org/eclipse/ditto/services/connectivity/messaging/persistence/ConnectionMongoSnapshotAdapter.java
index 6b50e00c85..c36eec8f41 100644
--- a/services/connectivity/messaging/src/main/java/org/eclipse/ditto/services/connectivity/messaging/persistence/ConnectionMongoSnapshotAdapter.java
+++ b/services/connectivity/messaging/src/main/java/org/eclipse/ditto/services/connectivity/messaging/persistence/ConnectionMongoSnapshotAdapter.java
@@ -10,8 +10,6 @@
  */
 package org.eclipse.ditto.services.connectivity.messaging.persistence;
 
-import javax.annotation.Nonnull;
-
 import org.eclipse.ditto.json.JsonObject;
 import org.eclipse.ditto.model.connectivity.Connection;
 import org.eclipse.ditto.services.utils.persistence.mongo.AbstractMongoSnapshotAdapter;
@@ -28,8 +26,7 @@ public ConnectionMongoSnapshotAdapter() {
     }
 
     @Override
-    protected Connection createJsonifiableFrom(@Nonnull final JsonObject jsonObject) {
-
+    protected Connection createJsonifiableFrom(final JsonObject jsonObject) {
         return ConnectionMigrationUtil.connectionFromJsonWithMigration(jsonObject);
     }
 
diff --git a/services/policies/persistence/src/main/java/org/eclipse/ditto/services/policies/persistence/actors/policy/PolicyPersistenceActor.java b/services/policies/persistence/src/main/java/org/eclipse/ditto/services/policies/persistence/actors/policy/PolicyPersistenceActor.java
index d1a23723b7..8bd4503d71 100755
--- a/services/policies/persistence/src/main/java/org/eclipse/ditto/services/policies/persistence/actors/policy/PolicyPersistenceActor.java
+++ b/services/policies/persistence/src/main/java/org/eclipse/ditto/services/policies/persistence/actors/policy/PolicyPersistenceActor.java
@@ -1862,7 +1862,8 @@ protected void apply(final C command) {
                     .flatMap(EntityTag::fromEntity)
                     .orElse(null);
 
-            log.debug("Validating conditional headers with currentETagValue <{}> on command <{}>.");
+            log.debug("Validating conditional headers with currentETagValue <{}> on command <{}>.", currentETagValue,
+                    command);
             try {
                 validator.checkConditionalHeaders(command, currentETagValue);
                 log.debug("Validating conditional headers succeeded.");
diff --git a/services/policies/persistence/src/main/java/org/eclipse/ditto/services/policies/persistence/serializer/PolicyMongoSnapshotAdapter.java b/services/policies/persistence/src/main/java/org/eclipse/ditto/services/policies/persistence/serializer/PolicyMongoSnapshotAdapter.java
index b75a9d3056..dd0d7cab63 100644
--- a/services/policies/persistence/src/main/java/org/eclipse/ditto/services/policies/persistence/serializer/PolicyMongoSnapshotAdapter.java
+++ b/services/policies/persistence/src/main/java/org/eclipse/ditto/services/policies/persistence/serializer/PolicyMongoSnapshotAdapter.java
@@ -10,7 +10,6 @@
  */
 package org.eclipse.ditto.services.policies.persistence.serializer;
 
-import javax.annotation.Nonnull;
 import javax.annotation.concurrent.ThreadSafe;
 
 import org.eclipse.ditto.json.JsonObject;
@@ -34,7 +33,7 @@ public PolicyMongoSnapshotAdapter() {
     }
 
     @Override
-    protected Policy createJsonifiableFrom(@Nonnull final JsonObject jsonObject) {
+    protected Policy createJsonifiableFrom(final JsonObject jsonObject) {
         return PoliciesModelFactory.newPolicy(jsonObject);
     }
 
diff --git a/services/policies/persistence/src/main/java/org/eclipse/ditto/services/policies/persistence/serializer/package-info.java b/services/policies/persistence/src/main/java/org/eclipse/ditto/services/policies/persistence/serializer/package-info.java
index 03aa13bcac..e3a8c8b737 100644
--- a/services/policies/persistence/src/main/java/org/eclipse/ditto/services/policies/persistence/serializer/package-info.java
+++ b/services/policies/persistence/src/main/java/org/eclipse/ditto/services/policies/persistence/serializer/package-info.java
@@ -8,6 +8,5 @@
  *
  * SPDX-License-Identifier: EPL-2.0
  */
-
 @org.eclipse.ditto.utils.jsr305.annotations.AllParametersAndReturnValuesAreNonnullByDefault
 package org.eclipse.ditto.services.policies.persistence.serializer;
diff --git a/services/utils/persistence/src/main/java/org/eclipse/ditto/services/utils/persistence/mongo/AbstractMongoSnapshotAdapter.java b/services/utils/persistence/src/main/java/org/eclipse/ditto/services/utils/persistence/mongo/AbstractMongoSnapshotAdapter.java
index 07bed3fd32..0ce59df5e8 100644
--- a/services/utils/persistence/src/main/java/org/eclipse/ditto/services/utils/persistence/mongo/AbstractMongoSnapshotAdapter.java
+++ b/services/utils/persistence/src/main/java/org/eclipse/ditto/services/utils/persistence/mongo/AbstractMongoSnapshotAdapter.java
@@ -14,7 +14,6 @@
 
 import java.text.MessageFormat;
 
-import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.ThreadSafe;
 
@@ -50,21 +49,9 @@ protected AbstractMongoSnapshotAdapter(final Logger logger) {
         this.logger = logger;
     }
 
-    /**
-     * This method is called exactly once when a snapshot is created. It does nothing by default. Subclasses
-     * may override it to inject code.
-     *
-     * @param snapshotEntity The entity for which the snapshot is created.
-     * @param json The JSON object to store as snapshot.
-     */
-    protected void onSnapshotStoreConversion(final T snapshotEntity, final JsonObject json) {
-        // does nothing by default
-    }
-
     @Override
     public Object toSnapshotStore(final T snapshotEntity) {
-        checkNotNull(snapshotEntity, "snapshot entity");
-        final JsonObject json = convertToJson(snapshotEntity);
+        final JsonObject json = convertToJson(checkNotNull(snapshotEntity, "snapshot entity"));
 
         onSnapshotStoreConversion(snapshotEntity, json);
 
@@ -72,6 +59,18 @@ public Object toSnapshotStore(final T snapshotEntity) {
         return dittoBsonJson.parse(json);
     }
 
+    /**
+     * This method is called exactly once when a snapshot is created.
+     * It does nothing by default.
+     * Subclasses may override it to inject code.
+     *
+     * @param snapshotEntity The entity for which the snapshot is created.
+     * @param json The JSON object to store as snapshot.
+     */
+    protected void onSnapshotStoreConversion(final T snapshotEntity, final JsonObject json) {
+        // does nothing by default
+    }
+
     @Override
     public T fromSnapshotStore(final SnapshotOffer snapshotOffer) {
         return convertSnapshotToJsonifiable(snapshotOffer.snapshot());
@@ -103,13 +102,13 @@ protected JsonObject convertToJson(final T snapshotEntity) {
      * @throws IllegalArgumentException if {@code rawSnapshotEntity} is not an instance of {@code DBObject}.
      */
     @Nullable
-    private T convertSnapshotToJsonifiable(@Nonnull final Object rawSnapshotEntity) {
+    private T convertSnapshotToJsonifiable(final Object rawSnapshotEntity) {
         final DBObject snapshotEntityAsDBObject = getSnapshotEntityAsDBObject(rawSnapshotEntity);
         final JsonObject jsonObject = convertToJson(snapshotEntityAsDBObject);
         return tryToCreateJsonifiableFrom(jsonObject);
     }
 
-    private static DBObject getSnapshotEntityAsDBObject(@Nonnull final Object rawSnapshotEntity) {
+    private static DBObject getSnapshotEntityAsDBObject(final Object rawSnapshotEntity) {
         checkNotNull(rawSnapshotEntity, "raw snapshot entity");
         if (!(rawSnapshotEntity instanceof DBObject)) {
             final String pattern = "Unable to create a Jsonifiable from <{0}>! Expected was a DBObject instance.";
@@ -127,7 +126,7 @@ private static DBObject getSnapshotEntityAsDBObject(@Nonnull final Object rawSna
      * @throws org.eclipse.ditto.model.base.exceptions.DittoJsonException if {@code dbObject} cannot be serialized to a
      * JsonObject.
      */
-    private static JsonObject convertToJson(@Nonnull final DBObject dbObject) {
+    private static JsonObject convertToJson(final DBObject dbObject) {
         checkNotNull(dbObject, "DBObject to be converted");
         final DittoBsonJson dittoBsonJson = DittoBsonJson.getInstance();
         final JsonObject jsonObject = dittoBsonJson.serialize(dbObject).asObject();
@@ -135,7 +134,7 @@ private static JsonObject convertToJson(@Nonnull final DBObject dbObject) {
     }
 
     @Nullable
-    private T tryToCreateJsonifiableFrom(@Nonnull final JsonObject jsonObject) {
+    private T tryToCreateJsonifiableFrom(final JsonObject jsonObject) {
         try {
             return createJsonifiableFrom(jsonObject);
         } catch (final JsonParseException | DittoRuntimeException e) {
@@ -152,6 +151,6 @@ private T tryToCreateJsonifiableFrom(@Nonnull final JsonObject jsonObject) {
      * @return the Jsonifiable which originates from {@code jsonObject}.
      * @throws org.eclipse.ditto.json.JsonParseException if {@code jsonObject} does not have the correct format.
      */
-    protected abstract T createJsonifiableFrom(@Nonnull JsonObject jsonObject);
+    protected abstract T createJsonifiableFrom(JsonObject jsonObject);
 
 }
diff --git a/services/utils/persistence/src/main/java/org/eclipse/ditto/services/utils/persistence/mongo/package-info.java b/services/utils/persistence/src/main/java/org/eclipse/ditto/services/utils/persistence/mongo/package-info.java
index 02e99d960b..d34bc22862 100644
--- a/services/utils/persistence/src/main/java/org/eclipse/ditto/services/utils/persistence/mongo/package-info.java
+++ b/services/utils/persistence/src/main/java/org/eclipse/ditto/services/utils/persistence/mongo/package-info.java
@@ -8,6 +8,5 @@
  *
  * SPDX-License-Identifier: EPL-2.0
  */
-
 @org.eclipse.ditto.utils.jsr305.annotations.AllParametersAndReturnValuesAreNonnullByDefault
 package org.eclipse.ditto.services.utils.persistence.mongo;