testGetHandler() {
    assertUndefined(
        'Event handler must be undefined before getHandler() ' +
            'is called',
        control.googUiComponentHandler_);
    /** @suppress {visibility} suppression added to enable type checking */
    const handler = control.getHandler();
    assertNotNull('Event handler must not be null', handler);
    assertEquals(
        'getHandler() must return the same instance if called again', handler,
        control.getHandler());
  }
Tests {@link Control#getHandler}.
@suppress {visibility} suppression added
     to enable type checking