it is done

core/src/mindustry/io/SaveMeta.java

@@ -0,0 +1,31 @@
+package mindustry.io;
+
+import arc.struct.*;
+import mindustry.game.*;
+import mindustry.maps.*;
+
+import static mindustry.Vars.maps;
+
+public class SaveMeta{
+    public int version;
+    public int build;
+    public long timestamp;
+    public long timePlayed;
+    public Map map;
+    public int wave;
+    public Rules rules;
+    public StringMap tags;
+    public String[] mods;
+
+    public SaveMeta(int version, long timestamp, long timePlayed, int build, String map, int wave, Rules rules, StringMap tags){
+        this.version = version;
+        this.build = build;
+        this.timestamp = timestamp;
+        this.timePlayed = timePlayed;
+        this.map = maps.all().find(m -> m.name().equals(map));
+        this.wave = wave;
+        this.rules = rules;
+        this.tags = tags;
+        this.mods = JsonIO.read(String[].class, tags.get("mods", "[]"));
+    }
+}