def default_site
      coord = coordinators.first if coordinators.size == 1
      site = coord.sites.first if coord and coord.sites.size == 1
      return site if site
      # If this CP's identifier was set by the client but the CP was not fetched, then do so now
      # in order to enable lazy-loading the sites.
      find if sites.empty? and identifier and not fetched?
      case sites.size
      when 1 then sites.first
      when 2 then sites.select { |site| site.name != CaTissue::Site.default_site.name }
      end
    end
def default_site
      coord = coordinators.first if coordinators.size == 1
      site = coord.sites.first if coord and coord.sites.size == 1
      return site if site
      # If this CP's identifier was set by the client but the CP was not fetched, then do so now
      # in order to enable lazy-loading the sites.
      find if sites.empty? and identifier and not fetched?
      case sites.size
      when 1 then sites.first
      when 2 then sites.select { |site| site.name != CaTissue::Site.default_site.name }
      end
    end
Returns the default protocol site, determined as follows:
 * If there is exactly one coordinator with one site, then the coordinator's site is the default.
 * Otherwise, if there is exactly one authorized site for this protocol, then that is the default site.
 * Otherwise, if there is exactly two authorized sites for this protocol, then the site other than the
   {CaTissue::Site.default_site} is returned.
 * Otherwise, this method returns nil.

 @return [CaTissue::Site, nil] the default site