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.clients.consumer.internals;
  
  import org.apache.kafka.common.TopicPartition;
  
  import java.util.Optional;
  import java.util.Set;
  
  /**
   * Listener for getting notified of membership state changes.
   */
  public interface MemberStateListener {
  
      /**
       * Called whenever epoch changes with new values received from the broker or
       * cleared if the member is not part of the group anymore (when it gets fenced, leaves the
       * group or fails).
       *
       * @param memberEpoch New member epoch received from the broker. Empty if the member is
       *                    not part of the group anymore.
       * @param memberId    Current member ID. It won't change until the process is terminated.
       */
      void onMemberEpochUpdated(Optional<Integer> memberEpoch, String memberId);
  
      /**
       * This callback is invoked when a group member's assigned set of partitions changes. Assignments can change via
       * group coordinator partition assignment changes, unsubscribing, and when leaving the group.
       *
       * @param partitions New assignment, can be empty, but not {@code null}
       */
      default void onGroupAssignmentUpdated(Set<TopicPartition> partitions) {
  
      }
  }
  