code: private KeyStroke getDefaultAccelerator(ZapMenuItem menuItem) {
  		if (isIdentifierWithDuplicatedAccelerator(menuItem.getIdentifier())) {
  			return null;
  		}
  		return menuItem.getDefaultAccelerator();
  	}
docs: Gets the default accelerator of the given menu, taken into account duplicated default accelerators.
  
  @param menuItem the menu item to return the default accelerator
  @return the KeyStroke or {@code null} if duplicated or does not have a default.