getConversationId(session) {
    if (
      session &&
      session.message &&
      session.message.address &&
      session.message.address.conversation
    ) {
      return session.message.address.conversation.id;
    }
    // eslint-disable-next-line no-underscore-dangle
    if (session && session._activity && session._activity.conversation) {
      // eslint-disable-next-line no-underscore-dangle
      return session._activity.conversation.id;
    }
    return undefined;
  }
Given a session instance of a chatbot, return the conversation identifier.
@param {Object} session Session instance of a message of chatbot.
@returns {String} Identifier of the conversation.