So, I was testing some item data output for a plugin i'm working on.
And i came across this strangely huge something... I'm not sure if it's a bug or a toggle somewhere... but when showing items, it's using the legacy materials, I made a command which shows the item type you're holding, and for 1.13 items it sends an NPE, aka the material type is null. This caught me as strange, so i tested some older blocks and items which had been renamed in the 1.13 update. such as Andesite, Granite, Dyes, Wool... ect. they all returned the legacy item names aka 'Stone' for andesite, granite, diorite (polished...) ect...
I thought it might just be a bug with an older 1.13.2 build (from BuildTools96) so i updated to BuildTools99 and got the new server jar. reset the server, loaded up the plugin, kaboomie, still same legacy items being refferenced. (basically i have the 1.13 items, but the plugin won't recognize them as actual material types, "trident, kelp, turtle-stuffs) and any items renamed in the 1.13 update are returning their legacy item name counterparts.