code: private JnlpFileHandlerHook createHook( String hookClass ) {
          if ( hookClass != null )
              try {
                  return Class.forName( hookClass ).asSubclass( JnlpFileHandlerHook.class ).newInstance();
              } catch ( InstantiationException | IllegalAccessException | ClassNotFoundException e ) {
                  _log.addWarning( "servlet.log.warning.failed-jnlp-file-hook", hookClass, e );
              }
          return JnlpFileHandlerHook.IDENTITY;
      }
docs: Creates the instance of the configured {@link JnlpFileHandlerHook}
  
  @param hookClass class
  @return the post-processor instance, never {@code null}