/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
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package org.apache.commons.collections4;

Marker interface for collections, maps and iterators that are unmodifiable.

This interface enables testing such as:

if (coll instanceof Unmodifiable) {
  coll = new ArrayList(coll);
}
// now we know coll is modifiable
 Of course all this only works if you use the Unmodifiable classes defined in this library. If you use the JDK unmodifiable class via java.util Collections then the interface won't be there. 
Since:
3.0/**
 * Marker interface for collections, maps and iterators that are unmodifiable.
 * <p>
 * This interface enables testing such as:
 * </p>
 * <pre>
 * if (coll instanceof Unmodifiable) {
 *   coll = new ArrayList(coll);
 * }
 * // now we know coll is modifiable
 * </pre>
 * Of course all this only works if you use the Unmodifiable classes defined
 * in this library. If you use the JDK unmodifiable class via {@code java.util Collections}
 * then the interface won't be there.
 *
 * @since 3.0
 */
public interface Unmodifiable {
    // marker interface - no methods to implement
}