diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/game/DownloadType.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/game/DownloadType.java
index 519fa141b..f314b3b5c 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/game/DownloadType.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/game/DownloadType.java
@@ -24,5 +24,7 @@ package org.jackhuang.hmcl.game;
 public enum DownloadType {
     CLIENT,
     SERVER,
-    WINDOWS_SERVER
+    WINDOWS_SERVER,
+    CLIENT_MAPPINGS,
+    SERVER_MAPPINGS
 }
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/game/Version.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/game/Version.java
index 7f912f011..ed187393a 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/game/Version.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/game/Version.java
@@ -24,6 +24,7 @@ import org.jackhuang.hmcl.util.Lang;
 import org.jackhuang.hmcl.util.Logging;
 import org.jackhuang.hmcl.util.StringUtils;
 import org.jackhuang.hmcl.util.ToStringBuilder;
+import org.jackhuang.hmcl.util.gson.JsonMap;
 import org.jackhuang.hmcl.util.gson.Validation;
 import org.jetbrains.annotations.Nullable;
 
@@ -60,8 +61,8 @@ public class Version implements Comparable<Version>, Validation {
     private final String assets;
     private final List<Library> libraries;
     private final List<CompatibilityRule> compatibilityRules;
-    private final Map<DownloadType, DownloadInfo> downloads;
-    private final Map<DownloadType, LoggingInfo> logging;
+    private final JsonMap<DownloadType, DownloadInfo> downloads;
+    private final JsonMap<DownloadType, LoggingInfo> logging;
     private final ReleaseType type;
     private final Date time;
     private final Date releaseTime;
@@ -103,8 +104,8 @@ public class Version implements Comparable<Version>, Validation {
         this.assets = assets;
         this.libraries = Lang.copyList(libraries);
         this.compatibilityRules = Lang.copyList(compatibilityRules);
-        this.downloads = downloads == null ? null : new HashMap<>(downloads);
-        this.logging = logging == null ? null : new HashMap<>(logging);
+        this.downloads = downloads == null ? null : new JsonMap<>(downloads);
+        this.logging = logging == null ? null : new JsonMap<>(logging);
         this.type = type;
         this.time = time == null ? null : (Date) time.clone();
         this.releaseTime = releaseTime == null ? null : (Date) releaseTime.clone();
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/gson/JsonMap.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/gson/JsonMap.java
new file mode 100644
index 000000000..7a065849f
--- /dev/null
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/gson/JsonMap.java
@@ -0,0 +1,51 @@
+/*
+ * Hello Minecraft! Launcher
+ * Copyright (C) 2019  huangyuhui <huanghongxun2008@126.com> and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package org.jackhuang.hmcl.util.gson;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * To resolve JsonParseException: duplicate key: null
+ * By skipping inserting data with key null
+ * @param <K>
+ * @param <V>
+ */
+public class JsonMap<K, V> extends HashMap<K, V> {
+    public JsonMap(int initialCapacity, float loadFactor) {
+        super(initialCapacity, loadFactor);
+    }
+
+    public JsonMap(int initialCapacity) {
+        super(initialCapacity);
+    }
+
+    public JsonMap() {
+        super();
+    }
+
+    public JsonMap(Map<? extends K, ? extends V> m) {
+        super(m);
+    }
+
+    @Override
+    public V put(K key, V value) {
+        if (key == null) return null;
+        return super.put(key, value);
+    }
+}