Likely that would be new ResourceLocation(Block#getRegistryName())   But then you'd have to load the block's blockstate and model files yourself to try and find textures. Any given block can have as many textures as it wants for as many blockstates as it wants.   Alternatively, you can get it's baked quads like so:   https://github.com/TheGreyGhost/MinecraftByExample/blob/master/src/main/java/minecraftbyexample/mbe04_block_dynamic_block_model1/CamouflageBakedModel.j