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1   /*
2    * Copyright (C) 2012 The Guava Authors
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    * http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  package com.google.common.base;
18  
19  import com.google.common.annotations.GwtCompatible;
20  import com.google.gwt.user.client.rpc.SerializationStreamReader;
21  import com.google.gwt.user.client.rpc.SerializationStreamWriter;
22  
23  /**
24   * Custom GWT serializer for {@link Absent}.
25   *
26   * <p>GWT can serialize an absent {@code Optional} on its own, but the resulting object is a
27   * different instance than the singleton {@code Absent.INSTANCE}, which breaks equality. We
28   * implement a custom serializer to maintain the singleton property.
29   *
30   * @author Chris Povirk
31   */
32  @GwtCompatible
33  public class Absent_CustomFieldSerializer {
34    public static void deserialize(SerializationStreamReader reader, Absent<?> instance) {}
35  
36    public static Absent<?> instantiate(SerializationStreamReader reader) {
37      return Absent.INSTANCE;
38    }
39  
40    public static void serialize(SerializationStreamWriter writer, Absent<?> instance) {}
41  }