Fix Forge experimental world suppression not working on first reopen

Author: embeddedt

forge/src/main/java/org/embeddedt/modernfix/forge/mixin/bugfix/extra_experimental_screen/CreateWorldScreenMixin.java

@@ -0,0 +1,24 @@
+package org.embeddedt.modernfix.forge.mixin.bugfix.extra_experimental_screen;
+
+import com.mojang.serialization.Lifecycle;
+import net.minecraft.client.gui.screens.worldselection.CreateWorldScreen;
+import net.minecraft.world.level.storage.PrimaryLevelData;
+import net.minecraft.world.level.storage.WorldData;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.ModifyArg;
+
+@Mixin(CreateWorldScreen.class)
+public class CreateWorldScreenMixin {
+    /**
+     * Fix experimental world dialog still being shown the first time you reopen a world that was created
+     * as experimental.
+     */
+    @ModifyArg(method = "createNewWorld", at = @At(value = "INVOKE", target = "Lnet/minecraft/client/gui/screens/worldselection/WorldOpenFlows;createLevelFromExistingSettings(Lnet/minecraft/world/level/storage/LevelStorageSource$LevelStorageAccess;Lnet/minecraft/server/ReloadableServerResources;Lnet/minecraft/core/RegistryAccess$Frozen;Lnet/minecraft/world/level/storage/WorldData;)V"), index = 3)
+    private WorldData setExperimentalFlag(WorldData data) {
+        if(data instanceof PrimaryLevelData pld && data.worldGenSettingsLifecycle() != Lifecycle.stable()) {
+            pld.withConfirmedWarning(true);
+        }
+        return data;
+    }
+}