Blockchain//Besu//ExtraData

- Clique extraData format: `0x` + 32 bytes vanity (64 zeros) + 20 bytes address (no 0x) + 65 bytes seal (130 zeros)

Clique extraData format: 0x + 32 bytes vanity (64 zeros) + 20 bytes address (no 0x) + 65 bytes seal (130 zeros)

The 20-byte middle section is where initial validator addresses are concatenated.

Multiple validators: concatenate their addresses back-to-back in the middle section.

The 65-byte seal at the end is reserved for the block signature — left as zeros in genesis.