Potion's and Splash Potions

So I’m having issues creating potions. I can’t find anything regarding splash potions. The current test code I have throws an error regarding the display name. if I comment out the custom display name no error, but the potion itself has no effect. So where have I gone wrong?

    ItemStack stack = WarpedLiterature.getGame().getRegistry().createItemBuilder().itemType(ItemTypes.POTION).quantity(1).build();

    stack.offer(Keys.DISPLAY_NAME, Texts.of("Test Potion"));
    
    List<PotionEffect> effects = new ArrayList<PotionEffect>();
    effects.add(WarpedLiterature.getGame().getRegistry().createPotionEffectBuilder().potionType(PotionEffectTypes.SLOWNESS).duration(200).build());
    stack.offer(Keys.POTION_EFFECTS, effects); 
    
    List<Text> lore = new ArrayList<Text>();
    lore.add(Texts.of("Blank"));
    stack.offer(Keys.ITEM_LORE, lore);

PotionEffects haven’t been implemented yet.

OK, and about the error and splash potions?

The lack of splash potions seems like an oversight in the API - issue opened here: Add PotionSplashData · Issue #907 · SpongePowered/SpongeAPI · GitHub