// Protocol Buffers - Google's data interchange format
// Copyright 2013 Google Inc.  All rights reserved.
// https://developers.google.com/protocol-buffers/
//
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//
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package com.google.protobuf.nano;

import java.util.HashMap;
import java.util.Map;

/**
 * Utility class for maps support.
 */
public final class MapFactories {
  public static interface MapFactory {
    <K, V> Map<K, V> forMap(Map<K, V> oldMap);
  }

  public static void setMapFactory(MapFactory newMapFactory) {
    mapFactory = newMapFactory;
  }

  public static MapFactory getMapFactory() {
    return mapFactory;
  }

  private static class DefaultMapFactory implements MapFactory {
    public <K, V> Map<K, V> forMap(Map<K, V> oldMap) {
      if (oldMap == null) {
        return new HashMap<K, V>();
      }
      return oldMap;
    }
  }
  private static volatile MapFactory mapFactory = new DefaultMapFactory();

  private MapFactories() {}
}

@@ -1898,39 +1898,318 @@
  oldMap);%0A  %7D%0A%0A 
+ // NOTE(liujisi): The factory setter is temporarily marked as package private.%0A  // The way to provide customized implementations of maps for different%0A  // platforms are still under discussion.  Mark it as private to avoid exposing%0A  // the API in proto3 alpha release.%0A  /*
  public
+ */
  static void set

Mark factory setter API as private for alpha release.