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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.eclipse.aether.util.graph.transformer;
20  
21  import org.eclipse.aether.RepositoryException;
22  import org.eclipse.aether.collection.DependencyGraphTransformationContext;
23  import org.eclipse.aether.collection.DependencyGraphTransformer;
24  import org.eclipse.aether.graph.DependencyNode;
25  
26  import static java.util.Objects.requireNonNull;
27  
28  /**
29   * A dependency graph transformer that does not perform any changes on its input.
30   */
31  public final class NoopDependencyGraphTransformer implements DependencyGraphTransformer {
32  
33      /**
34       * A ready-made instance of this dependency graph transformer which can safely be reused throughout an entire
35       * application regardless of multi-threading.
36       */
37      public static final DependencyGraphTransformer INSTANCE = new NoopDependencyGraphTransformer();
38  
39      /**
40       * Creates a new instance of this graph transformer. Usually, {@link #INSTANCE} should be used instead.
41       */
42      public NoopDependencyGraphTransformer() {}
43  
44      public DependencyNode transformGraph(DependencyNode node, DependencyGraphTransformationContext context)
45              throws RepositoryException {
46          requireNonNull(node, "node cannot be null");
47          requireNonNull(context, "context cannot be null");
48          return node;
49      }
50  }