private String copyClusterProperty(String propertyName, String instancePropertyName) {
    String value = getProperty(HDFS_SITE, propertyName, instancePropertyName);
    if (!StringUtils.isEmpty(value)) {
      conf.set(propertyName, value);
    }
    LOG.debug("set " + propertyName + " = " + value);
    return value;
  }
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