The event is not cancelable.
The event does not have a result.
It might be required for you to import the package if you encounter any issues (like casting an Array), so better be safe than sorry and add the import at the very top of the file.
Return Type: MCBlockState
MCBlockEvent.getBlockState() as MCBlockState myMCBlockEvent.getBlockState();
Return Type: BlockPos
MCBlockEvent.getPos() as BlockPos myMCBlockEvent.getPos();
Return Type: MCWorld
MCBlockEvent.getWorld() as MCWorld myMCBlockEvent.getWorld();