Better search backup group implementation

app/src/main/java/com/kunzisoft/keepass/database/element/database/DatabaseKDB.kt

@@ -178,19 +178,9 @@ class DatabaseKDB : DatabaseVersioned<Int, UUID, GroupKDB, EntryKDB>() {
      * Retrieve backup group with his name
      */
     private fun retrieveBackup(): GroupKDB? {
-        var backupGroup: GroupKDB? = null
+        return rootGroup?.searchChildGroup {
-        val groupHandler = object: NodeHandler<GroupKDB>() {
+            it.title.equals(BACKUP_FOLDER_TITLE, ignoreCase = true)
-            override fun operate(node: GroupKDB): Boolean {
-                return if (node.title.equals(BACKUP_FOLDER_TITLE, ignoreCase = true)) {
-                    backupGroup = node
-                    false
-                } else {
-                    true
-                }
-            }
         }
-        rootGroup?.doForEachChild(null, groupHandler)
-        return backupGroup
     }
 
     /**

app/src/main/java/com/kunzisoft/keepass/database/element/group/GroupVersionedInterface.kt

@@ -62,8 +62,27 @@ interface GroupVersionedInterface<Group: GroupVersionedInterface<Group, Entry>,
                     return false
             }
             if (doActionForChild)
-                group.doForEachChild(entryHandler, groupHandler)
+                group.doForEachChild(entryHandler, groupHandler, stopIterationWhenGroupHandlerOperateFalse)
         }
         return true
     }
+
+    fun searchChildGroup(criteria: (group: Group) -> Boolean): Group? {
+        return searchChildGroup(this, criteria)
+    }
+
+    private fun searchChildGroup(rootGroup: GroupVersionedInterface<Group, Entry>,
+                                 criteria: (group: Group) -> Boolean): Group? {
+        for (childGroup in rootGroup.getChildGroups()) {
+            if (criteria.invoke(childGroup)) {
+                return childGroup
+            } else {
+                val subGroup = searchChildGroup(childGroup, criteria)
+                if (subGroup != null) {
+                    return subGroup
+                }
+            }
+        }
+        return null
+    }
 }