public String getConfigurationProperty(String configurationType, String propertyName) {
    Map<String, String> configType = getConfigurationProperties(configurationType);
    if (null == configType) {
      return null;
    }

    return configType.get(propertyName);
  }
Gets a configuration value given the type and property name.

@param configurationType
         the configuration type, such as foo-site.
@param propertyName
         the property name, such as http.port
@return the property value, or {@code null} if it does not exist.
ambari-server-spi/src/main/java/org/apache/ambari/spi/ClusterInformation.java