Question try createBlockData got java.lang.NullPointerException: null

[creamgod45]

Server Version: paper-1.21.1-130.jar , paper-1.21.1-128.jar
JDK: 21

I have tried three ways to create it but none of them worked and the error message shown in the picture appeared. Does anyone have a better way?
error log

World world = player.getWorld();
Location location = player.getLocation();
BlockDisplay display = world.spawn(location, BlockDisplay.class);
// 1
display.setBlock(Material.END_CRYSTAL.createBlockData());
// 2
display.setBlock(Bukkit.createBlockData(Material.END_CRYSTAL));
// 3
BlockData blockData = player.getServer().createBlockData(Material.END_CRYSTAL);
display.setBlock(blockData);

 

[electronicboy]

end_crystal is not a block and thus, block data cannot exist for it

 

[creamgod45]

So do I need to try using ItemDisplay.class? Thanks

 

[creamgod45]

ItemDisplay itemDisplay = world.spawn(location, ItemDisplay.class, entity -> {
    entity.setItemStack(new ItemStack(Material.END_CRYSTAL));
});

int duration = 5 * 20; // duration of half a revolution (5 * 20 ticks = 5 seconds)

Matrix4f mat = new Matrix4f().scale(0.5F); // scale to 0.5x - smaller item
Bukkit.getScheduler().runTaskTimer(plugin, task -> {
    if (!itemDisplay.isValid()) { // display was removed from the world, abort task
        task.cancel();
        return;
    }

    itemDisplay.setTransformationMatrix(mat.rotateY(((float) Math.toRadians(180)) + 0.1F /* prevent the client from interpolating in reverse */));
    itemDisplay.setInterpolationDelay(0); // no delay to the interpolation
    itemDisplay.setInterpolationDuration(duration); // set the duration of the interpolated rotation
}, 1 /* delay the initial transformation by one tick from display creation */, duration);

what is this Material enum name

 

[stefvanschie]

The end crystal in the bottom image isn't a material, it's an entity.