precompute
fun <T : ExtendedInfo<T, E>, E : PrecomputedExtendedInfoEncoder<T>> T.precompute(allocator: ByteBufAllocator, huffmanCodecProvider: HuffmanCodecProvider)
A function to pre-compute this extended info block. Extended info blocks which do not support pre-computing (meaning they are observer-dependent) will build the buffer on-demand per observer.