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1   /*
2    * Copyright (C) 2008 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.collect;
18  
19  import com.google.common.annotations.GwtCompatible;
20  
21  /**
22   * Implementation of {@link ImmutableListMultimap} with no entries.
23   *
24   * @author Jared Levy
25   */
26  @GwtCompatible(serializable = true)
27  class EmptyImmutableListMultimap extends ImmutableListMultimap<Object, Object> {
28    static final EmptyImmutableListMultimap INSTANCE = new EmptyImmutableListMultimap();
29  
30    private EmptyImmutableListMultimap() {
31      super(ImmutableMap.<Object, ImmutableList<Object>>of(), 0);
32    }
33  
34    private Object readResolve() {
35      return INSTANCE; // preserve singleton property
36    }
37  
38    private static final long serialVersionUID = 0;
39  }