public class DemoBlock extends BlockWithEntity {
    [...]
    
    @Override
    public <T extends BlockEntity> BlockEntityTicker<T> getTicker(World world, BlockState state, BlockEntityType<T> type) {
        // Make sure to check world.isClient if you only want to tick only on serverside.
        return validateTicker(type, ExampleMod.DEMO_BLOCK_ENTITY, DemoBlockEntity::tick);
    }
}