Use a hash for remapped dependency caching. (#1277)

* Use a hash from ModDependencyOptions for remapped dependency caching.

* Use a different group to allow exclusiveContent to work.

* Fix unit tests

src/main/java/net/fabricmc/loom/util/CacheKey.java

@@ -0,0 +1,60 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2025 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.util;
+
+import java.nio.charset.StandardCharsets;
+import java.util.function.Supplier;
+
+import com.google.common.base.Suppliers;
+import org.gradle.api.Action;
+import org.gradle.api.Project;
+import org.gradle.api.tasks.Internal;
+
+import net.fabricmc.loom.util.gradle.GradleTypeAdapter;
+
+/**
+ * A simple base class for creating cache keys. Extend this class and create abstract properties to be included in the cache key.
+ */
+public abstract class CacheKey {
+	private static final int CHECKSUM_LENGTH = 8;
+	private final transient Supplier<String> jsonSupplier = Suppliers.memoize(() -> GradleTypeAdapter.GSON.toJson(this));
+	private final transient Supplier<String> cacheKeySupplier = Suppliers.memoize(() -> Checksum.sha1Hex(jsonSupplier.get().getBytes(StandardCharsets.UTF_8)).substring(0, CHECKSUM_LENGTH));
+
+	public static <T> T create(Project project, Class<T> clazz, Action<T> action) {
+		T instance = project.getObjects().newInstance(clazz);
+		action.execute(instance);
+		return instance;
+	}
+
+	@Internal
+	public final String getJson() {
+		return jsonSupplier.get();
+	}
+
+	@Internal
+	public final String getCacheKey() {
+		return cacheKeySupplier.get();
+	}
+}