Describe the bug
I'm trying to create a temporary region viewer for a plugin im working on, and I want to change all the blocks in a region for a short amount of time. Using the Multi_Block_Change packet, and using the PacketWrapper tutorials, but seems like multi block chages are not yet supported, just wanted to let the devs know :)

To Reproduce
Steps to reproduce the behavior:

1. Try to create a multi_block_change packet and you will not be able to set the chunk due to "ChunkCoordIntPair" doesnt exist in Version 1_16_R3?

Expected behavior
Not get an error and have a player see multiple blocks change in one go :)

Version Info
Dump File

Additional context
Error Message