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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *   http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing,
13   * software distributed under the License is distributed on an
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   * KIND, either express or implied.  See the License for the
16   * specific language governing permissions and limitations
17   * under the License.
18   */
19  package org.apache.maven.api.services;
20  
21  import java.util.ArrayList;
22  import java.util.Collection;
23  import java.util.Collections;
24  import org.apache.maven.api.Session;
25  import org.apache.maven.api.annotations.Experimental;
26  import org.apache.maven.api.annotations.Nonnull;
27  
28  /**
29   * Base class for requests.
30   *
31   * @since 4.0
32   */
33  @Experimental
34  abstract class BaseRequest {
35  
36      private final Session session;
37  
38      protected BaseRequest(@Nonnull Session session) {
39          this.session = nonNull(session, "session cannot be null");
40      }
41  
42      @Nonnull
43      public Session getSession() {
44          return session;
45      }
46  
47      public static <T> T nonNull(T obj, String message) {
48          if (obj == null) {
49              throw new IllegalArgumentException(message);
50          }
51          return obj;
52      }
53  
54      protected static <T> Collection<T> unmodifiable(Collection<T> obj) {
55          return obj != null && !obj.isEmpty()
56                  ? Collections.unmodifiableCollection(new ArrayList<>(obj))
57                  : Collections.emptyList();
58      }
59  }