Add support for multiple access wideners in Quilt mods

src/main/java/dev/architectury/loom/metadata/ModMetadataFile.java

@@ -1,6 +1,7 @@
 package dev.architectury.loom.metadata;
 
 import java.util.List;
+import java.util.Set;
 
 import org.jetbrains.annotations.Nullable;
 
@@ -14,9 +15,9 @@ public interface ModMetadataFile {
 	@Nullable String getId();
 
 	/**
-	 * {@return the path to the access widener file of this mod, or {@code null} if absent}.
+	 * {@return the paths to the access widener file of this mod, or an empty set if absent}.
 	 */
-	@Nullable String getAccessWidener();
+	Set<String> getAccessWideners();
 
 	/**
 	 * {@return the injected interface data in this mod metadata file}.

src/main/java/dev/architectury/loom/metadata/QuiltModJson.java

@@ -6,8 +6,10 @@ import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Objects;
+import java.util.Set;
 
 import com.google.gson.JsonArray;
 import com.google.gson.JsonElement;
@@ -18,6 +20,7 @@ import org.slf4j.LoggerFactory;
 
 import net.fabricmc.loom.LoomGradlePlugin;
 import net.fabricmc.loom.configuration.ifaceinject.InterfaceInjectionProcessor;
+import net.fabricmc.loom.util.function.CollectionUtil;
 
 public final class QuiltModJson implements JsonBackedModMetadataFile {
 	public static final String FILE_NAME = "quilt.mod.json";
@@ -68,22 +71,16 @@ public final class QuiltModJson implements JsonBackedModMetadataFile {
 	}
 
 	@Override
-	public @Nullable String getAccessWidener() {
+	public Set<String> getAccessWideners() {
 		if (json.has(ACCESS_WIDENER_KEY)) {
 			if (json.get(ACCESS_WIDENER_KEY).isJsonArray()) {
 				JsonArray array = json.get(ACCESS_WIDENER_KEY).getAsJsonArray();
-
-				// TODO (1.1): Support multiple access wideners in Quilt mods
-				if (array.size() != 1) {
-					throw new UnsupportedOperationException("Loom does not support multiple access wideners in one mod!");
-				}
-
-				return array.get(0).getAsString();
+				return CollectionUtil.mapTo(array, new LinkedHashSet<>(), JsonElement::getAsString);
 			} else {
-				return json.get(ACCESS_WIDENER_KEY).getAsString();
+				return Set.of(json.get(ACCESS_WIDENER_KEY).getAsString());
 			}
 		} else {
-			return null;
+			return Set.of();
 		}
 	}
 

src/main/java/net/fabricmc/loom/util/fmj/ModMetadataFabricModJson.java

@@ -27,6 +27,8 @@ package net.fabricmc.loom.util.fmj;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import java.util.function.Function;
+import java.util.stream.Collectors;
 
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
@@ -77,7 +79,8 @@ public final class ModMetadataFabricModJson extends FabricModJson {
 
 	@Override
 	public Map<String, ModEnvironment> getClassTweakers() {
-		@Nullable String accessWidener = modMetadata.getAccessWidener();
-		return accessWidener != null ? Map.of(accessWidener, ModEnvironment.UNIVERSAL) : Map.of();
+		return modMetadata.getAccessWideners()
+				.stream()
+				.collect(Collectors.toMap(Function.identity(), path -> ModEnvironment.UNIVERSAL));
 	}
 }

src/main/java/net/fabricmc/loom/util/function/CollectionUtil.java

@@ -83,13 +83,26 @@ public final class CollectionUtil {
 	 * @return a mutable list with the transformed entries
 	 */
 	public static <A, B> List<B> map(Iterable<? extends A> collection, Function<? super A, ? extends B> transform) {
-		ArrayList<B> result = new ArrayList<>();
+		return mapTo(collection, new ArrayList<>(), transform);
+	}
 
+	/**
+	 * Transforms the collection with a function, storing the results in a target collection.
+	 *
+	 * @param collection the source collection
+	 * @param target     the target collection
+	 * @param transform  the transformation function
+	 * @param <A> the source type
+	 * @param <B> the target type
+	 * @param <C> the target collection type
+	 * @return the target collection
+	 */
+	public static <A, B, C extends Collection<B>> C mapTo(Iterable<? extends A> collection, C target, Function<? super A, ? extends B> transform) {
 		for (A a : collection) {
-			result.add(transform.apply(a));
+			target.add(transform.apply(a));
 		}
 
-		return result;
+		return target;
 	}
 
 	/**