So, for some reason, IntelliJ isn't able to resolve the constructer. I really need some help with the properties.
public static final RegistryObject<Block> GRIMSTONESTAIRS= BLOCKS.register("grimstone_bricks_stairs",() -> new StairBlock(BlockBehaviour.Properties.of(Material.HEAVY_METAL).strength(1.5f,0.5f).sound(SoundType.DEEPSLATE)));
Really what happened was that this parameter you were passing:
worldIn.setBlock(pos, state, ... );
BlockState state = worldIn.getBlockState(pos);
when it should have been this: