Fix DeferredHolderCommon delegates not being references on Forge

loader-common/src/main/java/org/cyclops/cyclopscore/config/DeferredHolderCommon.java

@@ -144,18 +144,19 @@ protected Registry<R> getRegistry() {
     protected final void bind(boolean throwOnMissingRegistry) {
         if (this.holder != null) return;
 
-        // Check if we have an override for specific mod loaders
-        if (DeferredHolderCommon.BIND_OVERRIDE != null) {
-            this.holder = (Holder<R>) DeferredHolderCommon.BIND_OVERRIDE.apply(this.key);
-            if (this.holder != null) {
-                return;
-            }
-        }
-
+        // Bind via the registry first, as that gives us a Holder.Reference, which is required by delegates.
         Registry<R> registry = getRegistry();
         if (registry != null) {
             this.holder = registry.get(this.key).orElse(null);
-        } else if (throwOnMissingRegistry) {
+        }
+
+        // Check if we have an override for specific mod loaders,
+        // for entries that are not present in a regular registry.
+        if (this.holder == null && DeferredHolderCommon.BIND_OVERRIDE != null) {
+            this.holder = (Holder<R>) DeferredHolderCommon.BIND_OVERRIDE.apply(this.key);
+        }
+
+        if (this.holder == null && registry == null && throwOnMissingRegistry) {
             throw new IllegalStateException("Registry not present for " + this + ": " + this.key.registry());
         }
     }

loader-common/src/main/java/org/cyclops/cyclopscore/gametest/DeferredHolderCommonTest.java

@@ -0,0 +1,36 @@
+package org.cyclops.cyclopscore.gametest;
+
+import com.google.gson.JsonElement;
+import com.mojang.serialization.DataResult;
+import com.mojang.serialization.JsonOps;
+import net.minecraft.core.Holder;
+import net.minecraft.core.particles.ParticleType;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.gametest.framework.GameTestHelper;
+import org.cyclops.cyclopscore.RegistryEntriesCommon;
+import org.cyclops.cyclopscore.config.DeferredHolderCommon;
+
+/**
+ * Tests for {@link DeferredHolderCommon}.
+ * @author rubensworks
+ */
+public class DeferredHolderCommonTest {
+
+    // Registry#safeCastToReference only accepts Holder.Reference, so delegates must resolve to one.
+    @GameTest
+    public void testDelegateIsReference(GameTestHelper helper) {
+        Holder<ParticleType<?>> delegate = RegistryEntriesCommon.PARTICLE_BLUR.getDelegate();
+        helper.assertTrue(delegate instanceof Holder.Reference,
+                "Expected a Holder.Reference delegate, but got " + delegate);
+        helper.succeed();
+    }
+
+    @GameTest
+    public void testHolderCodecEncoding(GameTestHelper helper) {
+        DataResult<JsonElement> result = BuiltInRegistries.PARTICLE_TYPE.holderByNameCodec()
+                .encodeStart(JsonOps.INSTANCE, RegistryEntriesCommon.PARTICLE_BLUR);
+        helper.assertTrue(result.result().isPresent(), "Expected a successful encoding, but got " + result);
+        helper.succeed();
+    }
+
+}

loader-fabric/src/main/java/org/cyclops/cyclopscore/CyclopsCoreFabric.java

@@ -17,6 +17,7 @@
 import org.cyclops.cyclopscore.component.DataComponentCapacityConfig;
 import org.cyclops.cyclopscore.component.DataComponentEnergyStorageConfig;
 import org.cyclops.cyclopscore.config.ConfigHandlerCommon;
+import org.cyclops.cyclopscore.gametest.DeferredHolderCommonTest;
 import org.cyclops.cyclopscore.gametest.MethodGameTestInstanceConfig;
 import org.cyclops.cyclopscore.gametest.StartupTestFabric;
 import org.cyclops.cyclopscore.helper.CyclopsCoreInstance;
@@ -112,6 +113,6 @@ protected void onConfigsRegister(ConfigHandlerCommon configHandler) {
 
     @Override
     public Class<?>[] getGameTestClasses() {
-        return new Class[]{ StartupTestFabric.class };
+        return new Class[]{ StartupTestFabric.class, DeferredHolderCommonTest.class };
     }
 }

loader-forge/src/main/java/org/cyclops/cyclopscore/CyclopsCoreForge.java

@@ -25,6 +25,7 @@
 import org.cyclops.cyclopscore.config.ConfigHandlerCommon;
 import org.cyclops.cyclopscore.config.ConfigurableTypesForge;
 import org.cyclops.cyclopscore.config.DeferredHolderCommon;
+import org.cyclops.cyclopscore.gametest.DeferredHolderCommonTest;
 import org.cyclops.cyclopscore.gametest.MethodGameTestInstanceConfig;
 import org.cyclops.cyclopscore.gametest.StartupTestForge;
 import org.cyclops.cyclopscore.helper.CyclopsCoreInstance;
@@ -37,6 +38,8 @@
 import org.cyclops.cyclopscore.proxy.ICommonProxyCommon;
 import org.cyclops.cyclopscore.tracking.ImportantUsers;
 
+import java.util.Optional;
+
 /**
  * The main mod class of CyclopsCore.
  * @author rubensworks
@@ -62,6 +65,11 @@ public CyclopsCoreForge(FMLJavaModLoadingContext context) {
         DeferredHolderCommon.BIND_OVERRIDE = (key) -> {
             ForgeRegistry<Object> registry = RegistryManager.ACTIVE.getRegistry(key.registry());
             if (registry != null) {
+                // Prefer the registry's delegate, as only Holder.Reference can be serialized.
+                Optional<Holder.Reference<Object>> delegate = registry.getDelegate(key.identifier());
+                if (delegate.isPresent()) {
+                    return delegate.get();
+                }
                 Object value = registry.getValue(key.identifier());
                 if (value != null) {
                     return Holder.direct(value);
@@ -141,6 +149,6 @@ protected void onConfigsRegister(ConfigHandlerCommon configHandler) {
 
     @Override
     public Class<?>[] getGameTestClasses() {
-        return new Class[]{ StartupTestForge.class };
+        return new Class[]{ StartupTestForge.class, DeferredHolderCommonTest.class };
     }
 }

loader-neoforge/src/main/java/org/cyclops/cyclopscore/CyclopsCoreNeoForge.java

@@ -22,6 +22,7 @@
 import org.cyclops.cyclopscore.component.DataComponentFluidContentConfig;
 import org.cyclops.cyclopscore.component.DataComponentInventoryConfig;
 import org.cyclops.cyclopscore.config.ConfigHandlerCommon;
+import org.cyclops.cyclopscore.gametest.DeferredHolderCommonTest;
 import org.cyclops.cyclopscore.gametest.MethodGameTestInstanceConfig;
 import org.cyclops.cyclopscore.gametest.StartupTestNeoForge;
 import org.cyclops.cyclopscore.helper.CyclopsCoreInstance;
@@ -177,7 +178,7 @@ public void onConfigsRegister(ConfigHandlerCommon configHandler) {
 
     @Override
     public Class<?>[] getGameTestClasses() {
-        return new Class<?>[] { StartupTestNeoForge.class };
+        return new Class<?>[] { StartupTestNeoForge.class, DeferredHolderCommonTest.class };
     }
 
     private void loadComplete(FMLLoadCompleteEvent event) {