@Override
  public FileObject[] findJarFiles() throws KettleFileException {
    return findJarFiles( searchLibDir );
  }
@Test
  public void testFindJarFiles_ExceptionThrows() {
    String nullFolder = null;
    String expectedMessage = "Unable to list jar files in plugin folder '" + nullFolder + "'";

    plFolder = new PluginFolder( nullFolder, false, true );
    try {
      plFolder.findJarFiles();
      fail( "KettleFileException was not occured but expected." );
    } catch ( KettleFileException e ) {
      assertTrue( e instanceof KettleFileException );
      assertTrue( e.getLocalizedMessage().trim().startsWith( expectedMessage ) );
    }
  }