anchor.diff:  -spec dns_check_configuration_model() -> maps:map().
   dns_check_configuration_model() ->
       #{
  -        %% A collection of IP addresses for DNS servers used in checking DNS.
  +        %% A collection of IP addresses for DNS servers used in checking DNS. If
  +        %% empty, local system configuration will be used.
           dnsServers => {[string], optional},
  -        %% If true, DNS check will verify that control of DNS zone of
  +        %% If true, DNS check will verify that control of DNS zone for
           %% Onezone's domain was delegated to the DNS server built into
           %% Onezone service. This option is available only in Onezone service.
           builtInDnsServer => {boolean, optional},
  
positive.code: -spec dns_check_result_model() -> maps:map().
  dns_check_result_model() ->
      #{
          %% An interpreation of results obtained from DNS check. Possible values
          %% are: 'unresolvable' - query returned empty results;
          %% 'missing_records' - only some of the expected results were
          %% returned; 'bad_records' - none of the expected results were
  
negative.code:     }.
  
  %%--------------------------------------------------------------------
  %% @doc The Onezone custom configuration.
  %% @end
  %%--------------------------------------------------------------------
  -spec zone_configuration_onezone_model() -> maps:map().
  zone_configuration_onezone_model() ->
      #{
          %% The domain of Onezone cluster.
          domainName => {string, optional},
          %% The Onezone cluster name.
          name => {string, optional},
          %% If enabled the zone will use Let's Encrypt service to obtain SSL
          %% certificates. Otherwise certificates must be manually provided. By
          %% enabling this option you agree to the Let's Encrypt Subscriber
          %% Agreement.
          letsEncryptEnabled => {boolean, optional},
          %% If true, DNS check will verify that control of DNS zone for
          %% Onezone's domain was delegated to the DNS server built into
          %% Onezone service.
          builtInDnsServer => {boolean, optional},
          policies => {zone_policies_model(), optional}
      }.
  
  