{
  "apiKey": 11,
  "type": "request",
  "listeners": ["zkBroker", "broker"],
  "name": "JoinGroupRequest",
  // Version 1 adds RebalanceTimeoutMs.
  //
  // Version 2 and 3 are the same as version 1.
  //
  // Starting from version 4, the client needs to issue a second request to join group
  //
  // Starting from version 5, we add a new field called groupInstanceId to indicate member identity across restarts.
  // with assigned id.
  //
  // Version 6 is the first flexible version.
  //
  // Version 7 is the same as version 6.
  //
  // Version 8 adds the Reason field (KIP-800).
  "validVersions": "0-8",
  "flexibleVersions": "6+",
  "fields": [
    { "name": "GroupId", "type": "string", "versions": "0+", "entityType": "groupId",
      "about": "The group identifier." },
    { "name": "SessionTimeoutMs", "type": "int32", "versions": "0+",
      "about": "The coordinator considers the consumer dead if it receives no heartbeat after this timeout in milliseconds." },
    // Note: if RebalanceTimeoutMs is not present, SessionTimeoutMs should be
    // used instead.  The default of -1 here is just intended as a placeholder.
    { "name": "RebalanceTimeoutMs", "type": "int32", "versions": "1+", "default": "-1", "ignorable": true,
      "about": "The maximum time in milliseconds that the coordinator will wait for each member to rejoin when rebalancing the group." },
    { "name": "MemberId", "type": "string", "versions": "0+",
      "about": "The member id assigned by the group coordinator." },
    { "name": "GroupInstanceId", "type": "string", "versions": "5+", 
      "nullableVersions": "5+", "default": "null",
      "about": "The unique identifier of the consumer instance provided by end user." },
    { "name": "ProtocolType", "type": "string", "versions": "0+",
      "about": "The unique name the for class of protocols implemented by the group we want to join." },
    { "name": "Protocols", "type": "[]JoinGroupRequestProtocol", "versions": "0+",
      "about": "The list of protocols that the member supports.", "fields": [
      { "name": "Name", "type": "string", "versions": "0+", "mapKey": true,
        "about": "The protocol name." },
      { "name": "Metadata", "type": "bytes", "versions": "0+",
        "about": "The protocol metadata." }
    ]},
    // New Field //
    { "name": "Reason", "type": "string",
      "versions": "8+", "nullableVersions": "8+","default": "null",
      "about": "The reason why the member (re-)joins the group." }
  ]
}

/**
 * Remove members from the consumer group by given member identities.
 * <p>
 * For possible error codes, refer to {@link LeaveGroupResponse}.
 *
 * @param groupId The ID of the group to remove member from.
 * @param reason The reason why the member left the group.
 * @param options The options to carry removing members' information.
 * @return The MembershipChangeResult.
 */
RemoveMembersFromConsumerGroupResult removeMembersFromConsumerGroup(String groupId, String reason, RemoveMembersFromConsumerGroupOptions options);

/**
 * @see KafkaConsumer#enforceRebalance()
 */
void enforceRebalance(String reason);