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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

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/*
 * 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
 * limitations under the License.
 */
package org.apache.activemq.artemis.utils.collections;

import java.util.AbstractMap;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import java.util.Set;

/**
 * This class implements a Map, but actually doesnt store anything, it is similar in idea to an EmptyMap,
 * but where mutation methods simply do a no op rather than UnsupportedOperationException as with EmptyMap.
 *
 * This is used in QueueImpl when message groups is disabled.
 *
 * @param  the key type.
 * @param  the value type.
 */
public class NoOpMap extends AbstractMap {

   private static final Map NO_OP_MAP = new NoOpMap<>();

   @SuppressWarnings("unchecked")
   public static  Map instance() {
      return (Map) NO_OP_MAP;
   }

   private NoOpMap() {
   }

   @Override
   public V put(K key, V value) {
      return null;
   }

   @Override
   public int size() {
      return 0;
   }

   @Override
   public boolean isEmpty() {
      return true;
   }

   @Override
   public boolean containsKey(Object key) {
      return false;
   }

   @Override
   public boolean containsValue(Object value) {
      return false;
   }

   @Override
   public V get(Object key) {
      return null;
   }

   @Override
   public Set keySet() {
      return Collections.emptySet();
   }

   @Override
   public Collection values() {
      return Collections.emptySet();
   }

   @Override
   public Set> entrySet() {
      return Collections.emptySet();
   }

   @Override
   public boolean equals(Object o) {
      return (o instanceof Map) && ((Map)o).size() == 0;
   }

   @Override
   public int hashCode() {
      return 0;
   }
}