encodeGroupProtocols = ({ name, metadata = Buffer.alloc(0) }) => {
  return new Encoder().writeString(name).writeBytes(metadata)
}
JoinGroup Request (Version: 0) => group_id session_timeout member_id protocol_type [group_protocols]
  group_id => STRING
  session_timeout => INT32
  member_id => STRING
  protocol_type => STRING
  group_protocols => protocol_name protocol_metadata
    protocol_name => STRING
    protocol_metadata => BYTES