message: need to specify timestamp for v3 transactions
diff: @@ -3395,7 +3395,7 @@ UniValue importcoinstake(const JSONRPCRequest& request)
  "\nImport presigned coinstake for use in minting.\n",
  {
  {"coinstake", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "signed coinstake transaction as hex"},
  - {"timestamp", RPCArg::Type::NUM, RPCArg::Optional::NO, "timestamp when this coinstake will be valid"},
  + {"timestamp", RPCArg::Type::NUM, RPCArg::Optional::OMITTED, "timestamp when this coinstake will be valid"},
  },
  RPCResult{
  RPCResult::Type::STR, "txid", "transaction id if import is successful",
  @@ -3422,7 +3422,11 @@ UniValue importcoinstake(const JSONRPCRequest& request)
  {
  auto locked_chain = pwallet->chain().lock();
  - int timestamp = request.params[1].get_int();
  + int timestamp;
  + if (!request.params[1].isNull())
  + timestamp = request.params[1].get_int();
  + else
  + timestamp = tx->nTime;
  if (timestamp < GetTime()) {
  throw JSONRPCError(RPC_INVALID_PARAMETER, "Expired coinstake");
  