Hello, how can I write VoxelShape inside TileEntity-CompoundNBT tag?

Or if its not possible or not-effective, how do I fire event when Client player connects to the server?

I'm confused because there are three questions I could ask:

Are you changing the shape of your block?

Are you trying to write to a tile entity?

Are you trying to sync a tile entity to the client?

You may need to write it yourself (such as storing them in intarrays...etc)

and 

PlayerLoggedInEvent