The current blockstate and item model automatic creation/loading system, while working correctly, is not a forge recommended way to do it.
A rewrite of the system using DataGenerators will allow to not only generate models and blockstates, but also loottables, recipes and tags.
There are many good examples of a mods which use DataGenerators, one of them is in IE.

• Make a base class based on IE
• Item/Block Tag registration
• Blockstates
• Material Blocks
• Add generation for block slabs
• Item Models
• Loottables (no content)
• Recipes (IE adds recipes automatically for every metal)