public void registerClass( String key, String className ) {
    extendedClasses.put( key, className );
  }
@Test
  public void testRegisterClass() throws Exception {
    assertTrue( dialog.extendedClasses.isEmpty() );
    dialog.registerClass( "MyClass", "org.pentaho.test.MyClass" );
    assertFalse( dialog.extendedClasses.isEmpty() );
    assertEquals( "org.pentaho.test.MyClass", dialog.extendedClasses.get( "MyClass" ) );
  }