The Bukkit#recipeIterator incorrectly returns a recipe that changes a bone meal item into a white shulker box. It appears this is the standard recipe to dye the shulker box, however, missing a shulker box as the ingredient. 

I presume this is an issue with the translation of MC recipe objects into Spigot recipe objects, which could explain a lot of other bugs I've seen in the recipe APIs since 1.13

Offending code -> https://hub.spigotmc.org/stash/projects/SPIGOT/repos/craftbukkit/browse/nms-patches/RecipeShulkerBox.patch

This "bogus" data, while not used for MC recipes, is used for Bukkit's recipe API