Disable mapping wizard in Migration class

I was surprised that there appears to be no way to "turn off" the field mapping UI on a per-migration basis. You should be able to define a migration in code that is not to be messed with through the UI, yet still permit users to inspect the mappings. Something like $this->showFieldMappingUI = FALSE;

If you don't want to permit users to ever edit mappings through the UI, it's easy to disable it with a hook_menu_alter(). I.e....

/**
 * Implements hook_menu_alter.
 * Disable the edit mappings tab in all migrate wizards
 */
function MYMODULE_menu_alter(&$items) {
  $items['admin/content/migrate/groups/%/%/edit']['access callback'] = FALSE;
}