…eters."

  & Revert "Add pub key hashes to list of parties in on-chain head parameters.".

  After discussing the next steps, we realized that passing the pub key
  hashes on-chain and checking the PTs does not actually provide any
  extra security guarantees and only makes the on-chain code more
  complicated.

  In the end, this is something we can only truly handle off-chain,
  durign the observation of an init transaction. It is the observer who
  knows the configuration it is expecting, and that can decide whether
  some observation is valid or not.

  On-chain, there isn't much we can do since, anyone crafting the init
  transaction may also change the redeemer, parameters or anything
  really. The participants of a head are BY DEFINITION the keys
  identified by the PT. Now, those participants may or may not reflect a
  known configuration of a node, but this is decided off-chain
  exclusively.

  Use it for catching errors on an illed-formed init tx.

… reason.

  Whoopsie...

  Indeed... mutating outputs isn't caught by our guard because we only
  check minted values. Which is this however sufficient?

  (a) The ledger rules ensure that any minted value is actually properly
  distributed in outputs (transaction ins and outs must balance each
  other)

  (b) Our on-chain validator does ensure that the right number of assets
  are minted, in the right quantity, and that assets are distributed
  across the right number of outputs.