Implement item quick growth

src/main/java/emu/nebula/game/inventory/Inventory.java

@@ -537,11 +537,16 @@ public class Inventory extends PlayerManager implements GameDatabaseObject {
     
     // Utility functions
     
-    public PlayerChangeInfo produce(int id, int num) {
+    public PlayerChangeInfo produce(int id, int num, PlayerChangeInfo change) {
+        // Init change info
+        if (change == null) {
+            change = new PlayerChangeInfo();
+        }
+        
         // Get production data
         var data = GameData.getProductionDataTable().get(id);
         if (data == null) {
-            return null;
+            return change;
         }
         
         // Get materials
@@ -549,12 +554,9 @@ public class Inventory extends PlayerManager implements GameDatabaseObject {
         
         // Verify that we have the materials
         if (!this.verifyItems(materials)) {
-            return null;
+            return change;
         }
         
-        // Create change info
-        var change = new PlayerChangeInfo();
-        
         // Remove items
         this.removeItems(materials, change);
         

src/main/java/emu/nebula/game/player/PlayerChangeInfo.java

@@ -27,6 +27,10 @@ public class PlayerChangeInfo {
         return this;
     }
 
+    public boolean isEmpty() {
+        return this.list == null || this.list.isEmpty();
+    }
+
     public void add(ProtoMessage<?> proto) {
         var any = Any.newInstance()
                 .setTypeUrl(GameConstants.PROTO_BASE_TYPE_URL + proto.getClass().getSimpleName())