There are two separate models for shield blocking and non-blocking; when remodeling, which has 4 separate models of bows/crossbows, it has about 3-5 different models, Trowing, Holding, Etc, with tridents. I only added two models because it is a custom shield model and is not retextured a shield that already exsits. Open up the folder.zip, and you'll get your answer by looking through; there is an import TEXT file within the folder with my two java item models.

That is only if you're using optifine to remodel an already existing item with animations; if you're retexturing an item already in the game, then there is no need to add all these models; just add the texture. If you wish to learn more, join the discord linked below.