/**
  * This function retrieves the current instance of the metadata handler.
  * The metadata handler will be instantiated if this is the first call
  * to this function.
  *
  * @return SimpleSAML_Metadata_MetaDataStorageHandler The current metadata handler instance.
  */
 public static function getMetadataHandler()
 {
     if (self::$metadataHandler === null) {
         self::$metadataHandler = new SimpleSAML_Metadata_MetaDataStorageHandler();
     }
     return self::$metadataHandler;
 }