public <T> String getProperty(ConfigurationProperty<T> configurationProperty) {
    String defaultStringValue = null;
    if (null != configurationProperty.getDefaultValue()) {
      defaultStringValue = String.valueOf(configurationProperty.getDefaultValue());
    }

    return properties.getProperty(configurationProperty.getKey(), defaultStringValue);
  }
Gets the value for the specified {@link ConfigurationProperty}. If the
value hasn't been set then the default value as specified in
{@link ConfigurationProperty#getDefaultValue()} will be returned.

@param configurationProperty
@return
ambari-server/src/main/java/org/apache/ambari/server/configuration/Configuration.java