private void updateProperty(Cluster cluster, String configType, String propertyName, String newValue) throws AmbariException {
    Config config = cluster.getDesiredConfigByType(configType);
    if (config == null) {
      return;
    }
    String oldValue = config.getProperties().get(propertyName);
    if (oldValue != null) {
      Map<String, String> newProperty = new HashMap<>();
      newProperty.put(propertyName, newValue);
      updateConfigurationPropertiesForCluster(cluster, configType, newProperty, true, false);
    }
  }
Replace placeholder values in timeline reader address.
In Ambari 2.7 these properties are set to {{timeline_reader_address_http}} and {{timeline_reader_address_https}} and the stack code substitutes the proper host names.
In Ambari 2.7.1 the stack code no longer does this but the stack advisor and a SingleHostTopologyUpdater is responsible for replacing the hosts.
ambari-server/src/main/java/org/apache/ambari/server/upgrade/UpgradeCatalog271.java