[Feature request] More control over BlockEntityUpdatePacket prevention

[skippyall]

The problem

My polymer mod has an optional BlockEntityRenderer for my custom block which needs access to information in its BlockEntity. However, I don't think there is a way (excluding mixins) to prevent the BlockEntityUpdatePacket only if the client doesn't have the mod installed.

Possible solutions

• Allow passing a callback to registerBlockEntity (that might be a bit janky though)
• Add an interface for BlockEntity / BlockEntityType