подправил кеширование отображаемых данных ( чтобы не распаковывать каждый раз список имен групп и прочее)

src/Common/Database/DataSet.java

@@ -17,8 +17,8 @@ import java.util.Vector;
 import java.util.stream.Collectors;
 public class DataSet<K, D extends DBObject> extends DataSetAnchestor {
     //-
-    public static LinkedHashMap<Class, Object> selections = new LinkedHashMap<>();
-    //-
+    public LinkedHashMap<Class, Object> selections = new LinkedHashMap<>();
+    //---
     public String Name;
     public Class<K> k; //класс первичного ключа.
     public Class<D> d; //класс объектов.

src/Common/UI/VisualCache/ConfigurationCache.java

@@ -0,0 +1,57 @@
+package Common.UI.VisualCache;
+import Common.Global;
+import Common.Utils.Utils;
+import TestingSystem.Common.Configuration.Configuration;
+import TestingSystem.Common.Group.Group;
+import TestingSystem.Common.Group.Json.GroupJson;
+import TestingSystem.Common.Group.Json.GroupsJson;
+import TestingSystem.Common.Test.Json.TestJson;
+import TestingSystem.Common.Test.Json.TestsJson;
+import TestingSystem.Common.Test.Test;
+
+import java.util.Vector;
+public class ConfigurationCache extends VisualCache{
+    public GroupsJson groupsJson = null;
+    public Vector<String> groupsDescriptions = null;
+    public TestsJson testsJson = null;
+    //--
+    public ConfigurationCache(Configuration configuration) {
+        if (configuration.packedGroupsJson.isEmpty())
+            groupsJson = new GroupsJson(); //просто пустой
+        else
+            groupsJson = Utils.gson.fromJson(configuration.packedGroupsJson, GroupsJson.class);
+        //--
+        if (testsJson == null) {
+            if (configuration.packedTestsJson.isEmpty())
+                testsJson = new TestsJson(); //просто пустой
+            else
+                testsJson = Utils.gson.fromJson(configuration.packedTestsJson, TestsJson.class);
+        }
+        //-
+        groupsDescriptions = new Vector<>();
+        for (GroupJson groupJson : groupsJson.array)
+            groupsDescriptions.add(groupJson.description);
+    }
+    public int getTestsCount() {
+        return testsJson.array.size();
+    }
+    public Vector<String> getGroupsDescriptions() {
+        return groupsDescriptions;
+    }
+    public Vector<Group> getGroups(){
+        Vector<Group> groups = new Vector<>();
+        for (GroupJson groupJson : groupsJson.array){
+            if (Global.testingServer.db.groups.containsKey(groupJson.id))
+                groups.add(Global.testingServer.db.groups.get(groupJson.id));
+        }
+        return groups;
+    }
+    public Vector<Test> getTests(){
+        Vector<Test> tests = new Vector<>();
+        for (TestJson testJson : testsJson.array){
+            if (Global.testingServer.db.tests.containsKey(testJson.id))
+                tests.add(Global.testingServer.db.tests.get(testJson.id));
+        }
+        return tests;
+    }
+}

src/Common/UI/VisualCache/VisualCache.java

@@ -0,0 +1,3 @@
+package Common.UI.VisualCache;
+public class VisualCache {
+}

src/Common/UI/VisualCache/VisualCaches.java

@@ -0,0 +1,46 @@
+package Common.UI.VisualCache;
+import Common.Database.DBObject;
+import TestingSystem.Common.Configuration.Configuration;
+
+import java.util.LinkedHashMap;
+public class VisualCaches {
+    static LinkedHashMap<Class, LinkedHashMap<Object, VisualCache>> allData = new LinkedHashMap<>();
+    static LinkedHashMap<Object, VisualCache> getDataForClass(Class class_) {
+        LinkedHashMap<Object, VisualCache> data;
+        if (allData.containsKey(class_)) {
+            data = allData.get(class_);
+        } else {
+            data = new LinkedHashMap<>();
+            allData.put(class_, data);
+        }
+        return data;
+    }
+    //чтобы не трогать сами объекты и не сбить сериализацию
+    static VisualCache createCache(Object object) {
+        if (object instanceof Configuration)
+            return new ConfigurationCache((Configuration) object);
+        return new VisualCache();
+    }
+    public static VisualCache GetCache(DBObject object) {
+      //  System.out.println("get visual cache for " + object.getPK());
+        VisualCache res = null;
+        LinkedHashMap<Object, VisualCache> data = getDataForClass(object.getClass());
+        if (!data.containsKey(object.getPK())) {
+       //     System.out.println("cache not found, creating...");
+            data.put(object.getPK(), res = createCache(object));
+        } else {
+       //     System.out.println("cache found");
+            res = data.get(object.getPK());
+        }
+        return res;
+    }
+    public static void DeleteCahce(DBObject object){
+        DeleteCahce(object.getClass(), object.getPK());
+    }
+    public static void DeleteCahce(Class class_, Object pk){
+        LinkedHashMap<Object, VisualCache> data = getDataForClass(class_);
+        if (data.containsKey(pk))
+            data.remove(pk);
+
+    }
+}