update the toString

Author: hu-ahmed

connectivity/service/src/main/java/org/eclipse/ditto/connectivity/service/mapping/NormalizedMessageMapper.java

@@ -332,6 +332,7 @@ public String toString() {
         return getClass().getSimpleName() + " [" +
                 super.toString() +
                 ", jsonFieldSelector=" + jsonFieldSelector +
+                ", includeDeletedFields=" + includeDeletedFields +
                 "]";
     }
 }