public String getPropertyValue(String configType, String propertyName) {
    String value = null;
    if (properties.containsKey(configType) && properties.get(configType).containsKey(propertyName)) {
      value = properties.get(configType).get(propertyName);
    } else if (parentConfiguration != null) {
      value = parentConfiguration.getPropertyValue(configType, propertyName);
    }

    return value;
  }
Get the requested property value from the full merged set of properties.

@param configType    configuration type
@param propertyName  property name

@return requested property value or null if property isn't set in configuration hierarchy
ambari-server/src/main/java/org/apache/ambari/server/topology/Configuration.java