diff --git a/src/main/java/de/deadlocker8/budgetmaster/database/model/v4/BackupDatabase_v4.java b/src/main/java/de/deadlocker8/budgetmaster/database/model/v4/BackupDatabase_v4.java
index 096d4a51282ce8191da1691c77a6e6f9a77c9f1b..092e92280e3edf70ddeefb7bbbc42251b86f2601 100644
--- a/src/main/java/de/deadlocker8/budgetmaster/database/model/v4/BackupDatabase_v4.java
+++ b/src/main/java/de/deadlocker8/budgetmaster/database/model/v4/BackupDatabase_v4.java
@@ -13,10 +13,12 @@ public class BackupDatabase_v4 implements BackupDatabase
 	@SuppressWarnings("unused")
 	private final String TYPE = JSONIdentifier.BUDGETMASTER_DATABASE.toString();
 
-	@SuppressWarnings("FieldCanBeLocal")
+	@SuppressWarnings({"FieldCanBeLocal", "squid:S1170"})
+	// field can not be static, since static field won't be exported to JSON by GSON
 	private final int VERSION = 4;
 
-	@SuppressWarnings("unused")
+	@SuppressWarnings({"unused", "squid:S2065", "squid:S1170"})
+	// field can not be static, since static field won't be exported to JSON by GSON
 	private final transient String INTRODUCED_IN_VERSION = "v2.5.0";
 
 	private List<BackupCategory_v4> categories;
diff --git a/src/main/java/de/deadlocker8/budgetmaster/database/model/v5/BackupDatabase_v5.java b/src/main/java/de/deadlocker8/budgetmaster/database/model/v5/BackupDatabase_v5.java
index 1a7b3f666b3be7e78a3755e1978c7eebd316d2f1..c392a01d8f845324434b1f54a6c38d85a8e5d6f4 100644
--- a/src/main/java/de/deadlocker8/budgetmaster/database/model/v5/BackupDatabase_v5.java
+++ b/src/main/java/de/deadlocker8/budgetmaster/database/model/v5/BackupDatabase_v5.java
@@ -12,10 +12,12 @@ public class BackupDatabase_v5 implements BackupDatabase
 	@SuppressWarnings("unused")
 	private final String TYPE = JSONIdentifier.BUDGETMASTER_DATABASE.toString();
 
-	@SuppressWarnings("FieldCanBeLocal")
+	@SuppressWarnings({"FieldCanBeLocal", "squid:S1170"})
+	// field can not be static, since static field won't be exported to JSON by GSON
 	private final int VERSION = 5;
 
-	@SuppressWarnings("unused")
+	@SuppressWarnings({"unused", "squid:S2065", "squid:S1170"})
+	// field can not be static, since static field won't be exported to JSON by GSON
 	private final transient String INTRODUCED_IN_VERSION = "v2.6.0";
 
 	private List<BackupCategory_v5> categories;
diff --git a/src/main/java/de/deadlocker8/budgetmaster/database/model/v6/BackupDatabase_v6.java b/src/main/java/de/deadlocker8/budgetmaster/database/model/v6/BackupDatabase_v6.java
index 482bcc2d6c3a40d9efea843f1e2854081e17b733..fd13ef42a75b4d5bdffadfd5fb9700dd6425fad7 100644
--- a/src/main/java/de/deadlocker8/budgetmaster/database/model/v6/BackupDatabase_v6.java
+++ b/src/main/java/de/deadlocker8/budgetmaster/database/model/v6/BackupDatabase_v6.java
@@ -12,17 +12,18 @@ import de.deadlocker8.budgetmaster.database.model.v7.BackupIcon_v7;
 
 import java.util.ArrayList;
 import java.util.List;
-import java.util.stream.Collectors;
 
 public class BackupDatabase_v6 implements BackupDatabase
 {
 	@SuppressWarnings("unused")
 	private final String TYPE = JSONIdentifier.BUDGETMASTER_DATABASE.toString();
 
-	@SuppressWarnings("FieldCanBeLocal")
+	@SuppressWarnings({"FieldCanBeLocal", "squid:S1170"})
+	// field can not be static, since static field won't be exported to JSON by GSON
 	private final int VERSION = 6;
 
-	@SuppressWarnings("unused")
+	@SuppressWarnings({"unused", "squid:S2065", "squid:S1170"})
+	// field can not be static, since static field won't be exported to JSON by GSON
 	private final transient String INTRODUCED_IN_VERSION = "v2.7.0";
 
 	private List<BackupCategory_v5> categories;
diff --git a/src/main/java/de/deadlocker8/budgetmaster/database/model/v7/BackupDatabase_v7.java b/src/main/java/de/deadlocker8/budgetmaster/database/model/v7/BackupDatabase_v7.java
index f86d8f068f44c4130783ae123b43cb55ae858aa3..f288c8df71b042c17c7522336f310d8ea1111c7c 100644
--- a/src/main/java/de/deadlocker8/budgetmaster/database/model/v7/BackupDatabase_v7.java
+++ b/src/main/java/de/deadlocker8/budgetmaster/database/model/v7/BackupDatabase_v7.java
@@ -15,10 +15,12 @@ public class BackupDatabase_v7 implements BackupDatabase
 	@SuppressWarnings("unused")
 	private final String TYPE = JSONIdentifier.BUDGETMASTER_DATABASE.toString();
 
-	@SuppressWarnings("FieldCanBeLocal")
+	@SuppressWarnings({"FieldCanBeLocal", "squid:S1170"})
+	// field can not be static, since static field won't be exported to JSON by GSON
 	private final int VERSION = 7;
 
-	@SuppressWarnings("unused")
+	@SuppressWarnings({"unused", "squid:S2065", "squid:S1170"})
+	// field can not be static, since static field won't be exported to JSON by GSON
 	private final transient String INTRODUCED_IN_VERSION = "v2.8.0";
 
 	private List<BackupCategory_v7> categories;
diff --git a/src/main/java/de/deadlocker8/budgetmaster/database/model/v8/BackupDatabase_v8.java b/src/main/java/de/deadlocker8/budgetmaster/database/model/v8/BackupDatabase_v8.java
index e1d78144e3f946045183ab94758616e8a7bb7a1b..6625e9343d0d005a9c000847ff7431b1168e4d8c 100644
--- a/src/main/java/de/deadlocker8/budgetmaster/database/model/v8/BackupDatabase_v8.java
+++ b/src/main/java/de/deadlocker8/budgetmaster/database/model/v8/BackupDatabase_v8.java
@@ -25,10 +25,12 @@ public class BackupDatabase_v8 implements BackupDatabase
 	@SuppressWarnings("unused")
 	private final String TYPE = JSONIdentifier.BUDGETMASTER_DATABASE.toString();
 
-	@SuppressWarnings("FieldCanBeLocal")
+	@SuppressWarnings({"FieldCanBeLocal", "squid:S1170"})
+	// field can not be static, since static field won't be exported to JSON by GSON
 	private final int VERSION = 8;
 
-	@SuppressWarnings("unused")
+	@SuppressWarnings({"unused", "squid:S2065", "squid:S1170"})
+	// field can not be static, since static field won't be exported to JSON by GSON
 	private final transient String INTRODUCED_IN_VERSION = "v2.9.0";
 
 	private List<BackupCategory_v7> categories;