originSignaturePayload method Null safety
Implementation
Uint8List originSignaturePayload() {
var payloadForPreviousSignature = this.previousSignaturePayload();
return concatUint8List([
payloadForPreviousSignature,
this.previousPublicKey!,
Uint8List.fromList([this.previousSignature!.length]),
this.previousSignature!,
]);
}