{
  "apiKey": 11,
  "type": "request",
  "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.
  "validVersions": "0-7",
  "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." }
    ]}
  ]
}

{
  "apiKey": 11,
  "type": "response",
  "name": "JoinGroupResponse",
  // Version 1 is the same as version 0.
  //
  // Version 2 adds throttle time.
  //
  // Starting in version 3, on quota violation, brokers send out responses before throttling.
  //
  // Starting in version 4, the client needs to issue a second request to join group
  // with assigned id.
  //
  // Version 5 is bumped to apply group.instance.id to identify member across restarts.
  //
  // Version 6 is the first flexible version.
  //
  // Version 7 adds the Protocol Type.
  "validVersions": "0-7",
  "flexibleVersions": "6+",
  "fields": [
    { "name": "ThrottleTimeMs", "type": "int32", "versions": "2+", "ignorable": true,
      "about": "The duration in milliseconds for which the request was throttled due to a quota violation, or zero if the request did not violate any quota." },
    { "name": "ErrorCode", "type": "int16", "versions": "0+",
      "about": "The error code, or 0 if there was no error." },
    { "name": "GenerationId", "type": "int32", "versions": "0+", "default": "-1",
      "about": "The generation ID of the group." },
    // New Field
    { "name": "ProtocolType", "type": "string", "versions": "7+",
      "nullableVersions": "7+", "default": "null", "ignorable": true,
      "about": "The unique name the for class of protocols implemented by the group we want to join." },
    { "name": "ProtocolName", "type": "string", "versions": "0+",
      "about": "The group protocol selected by the coordinator." },
    { "name": "Leader", "type": "string", "versions": "0+",
      "about": "The leader of the group." },
    { "name": "MemberId", "type": "string", "versions": "0+",
      "about": "The member ID assigned by the group coordinator." },
    { "name": "Members", "type": "[]JoinGroupResponseMember", "versions": "0+", "fields": [
      { "name": "MemberId", "type": "string", "versions": "0+",
        "about": "The group member ID." },
      { "name": "GroupInstanceId", "type": "string", "versions": "5+",
        "nullableVersions": "5+", "default": "null",
        "about": "The unique identifier of the consumer instance provided by end user." },
      { "name": "Metadata", "type": "bytes", "versions": "0+",
        "about": "The group member metadata." }
    ]}
  ]
}

{
  "apiKey": 14,
  "type": "request",
  "name": "SyncGroupRequest",
  // Versions 1 and 2 are the same as version 0.
  //
  // Starting from version 3, we add a new field called groupInstanceId to indicate member identity across restarts.
  //
  // Version 4 is the first flexible version.
  //
  // Version 5 adds the Protocol Type.
  "validVersions": "0-5",
  "flexibleVersions": "4+",
  "fields": [
    { "name": "GroupId", "type": "string", "versions": "0+", "entityType": "groupId",
      "about": "The unique group identifier." },
    { "name": "GenerationId", "type": "int32", "versions": "0+",
      "about": "The generation of the group." },
    { "name": "MemberId", "type": "string", "versions": "0+",
      "about": "The member ID assigned by the group." },
    { "name": "GroupInstanceId", "type": "string", "versions": "3+", 
      "nullableVersions": "3+", "default": "null",
      "about": "The unique identifier of the consumer instance provided by end user." },
    // New Field
    { "name": "ProtocolType", "type": "string", "versions": "5+",
      "nullableVersions": "5+", "default": "null", "ignorable": true,
      "about": "The unique name the for class of protocols implemented by the group we want to join." },
    // New Field
    { "name": "ProtocolName", "type": "string", "versions": "5+",
      "nullableVersions": "5+", "default": "null", "ignorable": true,
      "about": "The group protocol name." },
    { "name": "Assignments", "type": "[]SyncGroupRequestAssignment", "versions": "0+",
      "about": "Each assignment.", "fields": [
      { "name": "MemberId", "type": "string", "versions": "0+",
        "about": "The ID of the member to assign." },
      { "name": "Assignment", "type": "bytes", "versions": "0+",
        "about": "The member assignment." }
    ]}
  ]
}

{
  "apiKey": 14,
  "type": "response",
  "name": "SyncGroupResponse",
  // Version 1 adds throttle time.
  //
  // Starting in version 2, on quota violation, brokers send out responses before throttling.
  //
  // Starting from version 3, syncGroupRequest supports a new field called groupInstanceId to indicate member identity across restarts.
  //
  // Version 4 is the first flexible version.
  //
  // Version 5 adds the Protocol Type.
  "validVersions": "0-5",
  "flexibleVersions": "4+",
  "fields": [
    { "name": "ThrottleTimeMs", "type": "int32", "versions": "1+", "ignorable": true,
      "about": "The duration in milliseconds for which the request was throttled due to a quota violation, or zero if the request did not violate any quota." },
    { "name": "ErrorCode", "type": "int16", "versions": "0+",
      "about": "The error code, or 0 if there was no error." },
    // New Fields
    { "name": "ProtocolType", "type": "string", "versions": "5+",
      "nullableVersions": "5+", "default": "null", "ignorable": true,
      "about": "The unique name the for class of protocols implemented by the group we want to join." },
    // New Field
    { "name": "ProtocolName", "type": "string", "versions": "5+",
      "nullableVersions": "5+", "default": "null", "ignorable": true,
      "about": "The group protocol name." },
    { "name": "Assignment", "type": "bytes", "versions": "0+",
      "about": "The member assignment." }
  ]
}