ExpiredSignedPreKey
class ExpiredSignedPreKey(val address: DeviceAddress, val signedPreKeyId: SignedPreKeyId) : SecureMessageClientException
address sent a new session initiation that names the local signed prekey signedPreKeyId, whose grace period is over (see docs/signed-prekey-lifecycle.md). Its private key is deleted or about to be, so no new session can be accepted with it. Nothing was changed. Existing sessions are not affected.