code: public void setType(String type) {
          if (type == null) {
              _properties.remove(AMQP_PROP_TYPE);
              return;
          }
          
          _properties.put(AMQP_PROP_TYPE, type);
      }
docs: Sets the value of "type" property. If a null value is passed
  in, it indicates that the property is not set.
  
  @param  type    value of "type" property