Type Alias UpgradeRestrictionSignal

UpgradeRestrictionSignal: StorageDescriptor<[Key: number], UpgradeRestriction, true>

This is used by the relay-chain to communicate that there are restrictions for performing an upgrade for this parachain.

This may be a because the parachain waits for the upgrade cooldown to expire. Another potential use case is when we want to perform some maintenance (such as storage migration) we could restrict upgrades to make the process simpler.

NOTE that this field is used by parachains via merkle storage proofs, therefore changing the format will require migration of parachains.