class Rack::Protection::EncryptedCookie

def write_session(req, session_id, session, _options)
  session = session.merge('session_id' => session_id)
  session_data = coder.encode(session)
  unless @secrets.empty?
    session_data = Rack::Protection::Encryptor.encrypt_message(session_data, @secrets.first)
  end
  if session_data.size > (4096 - @key.size)
    req.get_header(RACK_ERRORS).puts('Warning! Rack::Protection::EncryptedCookie data size exceeds 4K.')
    nil
  else
    session_data
  end
end