Fix #429

HMCLCore/src/main/java/org/jackhuang/hmcl/download/VersionList.java

@@ -70,7 +70,7 @@ public abstract class VersionList<T extends RemoteVersion> {
         });
     }
 
-    private Collection<T> getVersionsImpl(String gameVersion) {
+    protected Collection<T> getVersionsImpl(String gameVersion) {
         lock.readLock().lock();
         try {
             return versions.get(gameVersion);

HMCLCore/src/main/java/org/jackhuang/hmcl/download/game/GameVersionList.java

@@ -44,6 +44,16 @@ public final class GameVersionList extends VersionList<GameRemoteVersion> {
         return true;
     }
 
+    @Override
+    protected Collection<GameRemoteVersion> getVersionsImpl(String gameVersion) {
+        lock.readLock().lock();
+        try {
+            return versions.values();
+        } finally {
+            lock.readLock().unlock();
+        }
+    }
+
     @Override
     public Task refreshAsync(DownloadProvider downloadProvider) {
         GetTask task = new GetTask(NetworkUtils.toURL(downloadProvider.getVersionListURL()));