content: /*
   * 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.kafka.common.internals;
  
  import org.apache.kafka.common.ClusterResource;
  import org.apache.kafka.common.ClusterResourceListener;
  
  import java.util.ArrayList;
  import java.util.List;
  
  public class ClusterResourceListeners {
  
      private final List<ClusterResourceListener> clusterResourceListeners;
  
      public ClusterResourceListeners() {
          this.clusterResourceListeners = new ArrayList<>();
      }
  
      /**
       * Add only if the candidate implements {@link ClusterResourceListener}.
       * @param candidate Object which might implement {@link ClusterResourceListener}
       */
      public void maybeAdd(Object candidate) {
          if (candidate instanceof ClusterResourceListener) {
              clusterResourceListeners.add((ClusterResourceListener) candidate);
          }
      }
  
      /**
       * Add all items who implement {@link ClusterResourceListener} from the list.
       * @param candidateList List of objects which might implement {@link ClusterResourceListener}
       */
      public void maybeAddAll(List<?> candidateList) {
          for (Object candidate : candidateList) {
              this.maybeAdd(candidate);
          }
      }
  
      /**
       * Send the updated cluster metadata to all {@link ClusterResourceListener}.
       * @param cluster Cluster metadata
       */
      public void onUpdate(ClusterResource cluster) {
          for (ClusterResourceListener clusterResourceListener : clusterResourceListeners) {
              clusterResourceListener.onUpdate(cluster);
          }
      }
  }