Reviving this 6 year old issue as it seems there's still interest in a multi block change API. `Player#sendChunkChange()` has since been removed (as of 1.16), so I've introduced an alternative `Player#sendBlockChanges(boolean, Consumer<BlockChangeDelegate>)`. The PRs are awaiting review and approval under bukkit#789 and craftbukkit#1108

You could always consider making a PR for this if you're aware of how to do it in a sane manner.

Pretty sure that it's out of scope for the bukkit API then (though I might be wrong) - it's not supposed to be used for manual packet handling/sending and low-level things like that, for better or worse. While there are existing methods that are like what you describe, both of them (Player.sendBlockChange and Player.sendChunkChange) are deprecated and sendChunkChange flat-out doesn't work anymore.

If you want to handle packets, you should consider using ProtocolLib, which (while it still uses reflection internally) wraps everything into a far cleaner API.

Yes but you can't send false packet with it and, if you want to create something a little bit low-level (like placing block differently) then you can't send the packet because there's no api for it and you need to use reflection

The block change packet to send is selected automatically by the server - no special handling is needed. It automatically uses MultiBlockChange when needed. (See PlayerChunkMap.flagDirty)