@staticmethod
def merge_extinfo(service, extinfo):
    """Merge extended host information into a service

        :param service: the service to edit
        :type service: alignak.objects.service.Service
        :param extinfo: the external info we get data from
        :type extinfo: alignak.objects.serviceextinfo.ServiceExtInfo
        :return: None
        """
    properties = ['notes', 'notes_url', 'icon_image', 'icon_image_alt']
    for prop in properties:
        if getattr(service, prop) == '' and getattr(extinfo, prop) != '':
            setattr(service, prop, getattr(extinfo, prop))
