private String getProperty(String type, String key) {
    if (context.getCluster() != null) {
      return context.getCluster().getConfigurationValue(type, key);
    }
    return null;
  }
takes context and any extra custom properties that needs to be included into config
@param context
@param customProperties
contrib/views/utils/src/main/java/org/apache/ambari/view/utils/hdfs/ConfigurationBuilder.java