kdbx4.1: keep track of PreviousParentGroup

lib/src/kdbx_header.dart

@@ -71,6 +71,7 @@ class KdbxVersion {
   static const V3 = KdbxVersion._(3, 0);
   static const V3_1 = KdbxVersion._(3, 1);
   static const V4 = KdbxVersion._(4, 0);
+  static const V4_1 = KdbxVersion._(4, 1);
 
   final int major;
   final int minor;

lib/src/kdbx_object.dart

@@ -192,6 +192,9 @@ abstract class KdbxObject extends KdbxNode {
 
   KdbxGroup? _parent;
 
+  late final UuidNode previousParentGroup =
+      UuidNode(this, 'PreviousParentGroup');
+
   KdbxCustomIcon? get customIcon =>
       customIconUuid.get()?.let((uuid) => file!.body.meta.customIcons[uuid]);
 
@@ -237,7 +240,10 @@ abstract class KdbxObject extends KdbxNode {
 
   @internal
   void internalChangeParent(KdbxGroup? parent) {
-    modify(() => _parent = parent);
+    modify(() {
+      previousParentGroup.set(_parent?.uuid);
+      _parent = parent;
+    });
   }
 
   void merge(MergeContext mergeContext, covariant KdbxObject other);

lib/src/kdbx_xml.dart

@@ -28,6 +28,7 @@ class KdbxXml {
   static const ATTR_ID = 'ID';
   static const NODE_BINARY = 'Binary';
   static const ATTR_REF = 'Ref';
+  static const NODE_PREVIOUS_PARENT_GROUP = 'PreviousParentGroup';
   static const NODE_CUSTOM_ICONS = 'CustomIcons';
 
   /// CustomIcons >> Icon

test/deleted_objects_test.dart

@@ -25,6 +25,18 @@ void main() {
       expect(reload.body.deletedObjects, hasLength(1));
     });
   });
+  group('delete to trash', () {
+    test('move to trash, read previous parent', () {
+      final file = testUtil.createEmptyFile();
+      final g = file.body.rootGroup;
+      final entry = testUtil.createEntry(file, g, 'foo', 'bar');
+      expect(g.getAllGroupsAndEntries(), hasLength(2));
+      file.deleteEntry(entry);
+      // root group, entry and trash group.
+      expect(g.getAllGroupsAndEntries(), hasLength(3));
+      expect(entry.previousParentGroup.get(), g.uuid);
+    });
+  });
   group('delete permanently', () {
     test('delete entry', () async {
       final file = testUtil.createEmptyFile();