Don't serialize empty maps

pack-schema/api/src/main/java/org/geysermc/pack/bedrock/resource/BedrockResourcePack.java

@@ -37,6 +37,7 @@ import org.geysermc.pack.bedrock.resource.textures.TerrainTexture;
 import org.geysermc.pack.bedrock.resource.textures.itemtexture.TextureData;
 import org.geysermc.pack.bedrock.resource.textures.terraintexture.texturedata.Textures;
 import org.geysermc.pack.util.gson.EmptyArrayAdapterFactory;
+import org.geysermc.pack.util.gson.EmptyMapAdapterFactory;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -56,6 +57,7 @@ public class BedrockResourcePack {
             .disableHtmlEscaping()
             .setPrettyPrinting()
             .registerTypeAdapterFactory(new EmptyArrayAdapterFactory())
+            .registerTypeAdapterFactory(new EmptyMapAdapterFactory())
             .create();
 
     private final Path directory;

pack-schema/api/src/main/java/org/geysermc/pack/util/gson/EmptyArrayAdapterFactory.java

@@ -35,14 +35,16 @@ import com.google.gson.stream.JsonWriter;
 
 import java.io.IOException;
 import java.util.Collection;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 public class EmptyArrayAdapterFactory implements TypeAdapterFactory {
 
     @Override
     public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
         Class<?> rawType = type.getRawType();
-        if (!List.class.isAssignableFrom(rawType)) {
+        if (!Collection.class.isAssignableFrom(rawType)) {
             return null;
         }
 

pack-schema/api/src/main/java/org/geysermc/pack/util/gson/EmptyMapAdapterFactory.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2019-2023 GeyserMC. http://geysermc.org
+ *
+ *  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.
+ *
+ *  @author GeyserMC
+ *  @link https://github.com/GeyserMC/PackConverter
+ *
+ */
+
+package org.geysermc.pack.util.gson;
+
+import com.google.gson.Gson;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+
+import java.io.IOException;
+import java.util.Map;
+
+public class EmptyMapAdapterFactory implements TypeAdapterFactory {
+
+    @Override
+    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+        Class<?> rawType = type.getRawType();
+        if (!Map.class.isAssignableFrom(rawType)) {
+            return null;
+        }
+
+        TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type);
+
+        return new TypeAdapter<T>() {
+
+            @Override
+            public T read(JsonReader in) throws IOException {
+                return delegate.read(in);
+            }
+
+            @Override
+            public void write(JsonWriter out, T value) throws IOException {
+                delegate.write(out, (value == null || value instanceof Map<?, ?> map && map.isEmpty()) ? null : value);
+            }
+        };
+    }
+}