code: function Message (data, headers, deliveryInfo) {
          assert.object(data);
          assert.object(headers);
          assert.object(deliveryInfo);
  
          this.data = Message.factory(data, deliveryInfo.type);
          this.headers = headers;
          this.deliveryInfo = deliveryInfo;
      }
docs: Constructor for a message
  
  @param {*} messenger
  @param {Object} data
  @param {*} [options]
  @constructor