Biome modification API small enhancements (#2789)

* Allow OptionalInt in BiomeModificationContext

For some reason, vanilla uses `Optional<Integer>` instead of
the preferred `OptionalInt`. Add an override that allows passing
`OptionalInt`. For consistency with vanilla, the old method is NOT
deprecated.

* Do not rely on Identifier identity when checking registration

`Identifier` is a value-based class and should never be compared
using `==`. Luckily, this does not cause bugs right now.
(Using `equals` is worse, since it'll prevent spawning pigs.)
Instead use the proper method of checking if an entry is registered.

* Fix #2079

(cherry picked from commit b5d379b004)

fabric-biome-api-v1/src/main/java/net/fabricmc/fabric/api/biome/v1/BiomeModificationContext.java

@@ -17,6 +17,7 @@
 package net.fabricmc.fabric.api.biome.v1;
 
 import java.util.Optional;
+import java.util.OptionalInt;
 import java.util.function.BiPredicate;
 
 import org.jetbrains.annotations.NotNull;
@@ -129,6 +130,14 @@ public interface BiomeModificationContext {
 			setFoliageColor(Optional.of(color));
 		}
 
+		/**
+		 * @see BiomeEffects#getFoliageColor()
+		 * @see BiomeEffects.Builder#foliageColor(int)
+		 */
+		default void setFoliageColor(OptionalInt color) {
+			color.ifPresentOrElse(this::setFoliageColor, this::clearFoliageColor);
+		}
+
 		/**
 		 * @see BiomeEffects#getFoliageColor()
 		 * @see BiomeEffects.Builder#foliageColor(int)
@@ -151,6 +160,14 @@ public interface BiomeModificationContext {
 			setGrassColor(Optional.of(color));
 		}
 
+		/**
+		 * @see BiomeEffects#getGrassColor()
+		 * @see BiomeEffects.Builder#grassColor(int)
+		 */
+		default void setGrassColor(OptionalInt color) {
+			color.ifPresentOrElse(this::setGrassColor, this::clearGrassColor);
+		}
+
 		/**
 		 * @see BiomeEffects#getGrassColor()
 		 * @see BiomeEffects.Builder#grassColor(int)

fabric-biome-api-v1/src/main/java/net/fabricmc/fabric/impl/biome/modification/BiomeModificationContextImpl.java

@@ -31,6 +31,7 @@ import com.google.common.base.Suppliers;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import net.minecraft.entity.EntityType;
 import net.minecraft.entity.SpawnGroup;
@@ -302,7 +303,11 @@ public class BiomeModificationContextImpl implements BiomeModificationContext {
 		@Override
 		public boolean removeCarver(GenerationStep.Carver step, RegistryKey<ConfiguredCarver<?>> configuredCarverKey) {
 			ConfiguredCarver<?> carver = carvers.getOrThrow(configuredCarverKey);
-			List<RegistryEntry<ConfiguredCarver<?>>> genCarvers = new ArrayList<>(generationSettings.carvers.get(step).stream().toList());
+			RegistryEntryList<ConfiguredCarver<?>> carvers = generationSettings.carvers.get(step);
+
+			if (carvers == null) return false;
+
+			List<RegistryEntry<ConfiguredCarver<?>>> genCarvers = new ArrayList<>(carvers.stream().toList());
 
 			if (genCarvers.removeIf(entry -> entry.value() == carver)) {
 				generationSettings.carvers.put(step, RegistryEntryList.of(genCarvers));
@@ -312,7 +317,9 @@ public class BiomeModificationContextImpl implements BiomeModificationContext {
 			return false;
 		}
 
-		private <T> RegistryEntryList<T> plus(RegistryEntryList<T> values, RegistryEntry<T> entry) {
+		private <T> RegistryEntryList<T> plus(@Nullable RegistryEntryList<T> values, RegistryEntry<T> entry) {
+			if (values == null) return RegistryEntryList.of(entry);
+
 			List<RegistryEntry<T>> list = new ArrayList<>(values.stream().toList());
 			list.add(entry);
 			return RegistryEntryList.of(list);