it is done

core/src/mindustry/game/Objective.java

@@ -0,0 +1,27 @@
+package mindustry.game;
+
+import arc.scene.ui.layout.*;
+import arc.util.ArcAnnotate.*;
+import mindustry.game.Objectives.*;
+import mindustry.type.*;
+
+/** Defines a specific objective for a game. */
+public interface Objective{
+
+    /** @return whether this objective is met. */
+    boolean complete();
+
+    /** @return the string displayed when this objective is completed, in imperative form.
+     * e.g. when the objective is 'complete 10 waves', this would display "complete 10 waves".
+     * If this objective should not be displayed, should return null.*/
+    @Nullable String display();
+
+    /** Build a display for this zone requirement.*/
+    default void build(Table table){
+
+    }
+
+    default Zone zone(){
+        return this instanceof ZoneObjective ? ((ZoneObjective)this).zone : null;
+    }
+}