This differs from behaviour of `importaddress` where it works.
```
$ bitcoin-cli importaddress "<address>" "<label>" false
```
vs
```
$ bitcoin-cli importmulti '[{ "scriptPubKey": { "address": "<address>" }, "timestamp":0, "label": "<label>", "watchonly": true }]' '{ "rescan": false }'
error code: -13
error message:
Error: Please enter the wallet passphrase with walletpassphrase first.
```
CHECK_NONFATAL(wallet.chain().findBlock(wallet.GetLastBlockHash(), FoundBlock().time(block_time)));
    // 
    // 
    LOCK(spk_man.cs_KeyStore);
    const std::map<CKeyID, int64_t>& mapKeyPool = spk_man.GetAllReserveKeys();
    std::set<CScriptID> scripts = spk_man.GetCScripts();
    // 
    std::vector<std::pair<int64_t, CKeyID> > vKeyBirth;
    for (const auto& entry : mapKeyBirth) {
        vKeyBirth.push_back(std::make_pair(entry.second, entry.first));
    }
    mapKeyBirth.clear();
    std::sort(vKeyBirth.begin(), vKeyBirth.end());
    // 
    file << strprintf("# Wallet dump created by %s %s\n", PACKAGE_NAME, FormatFullVersion());
    file << strprintf("# * Created on %s\n", FormatISO8601DateTime(GetTime()));
    file << strprintf("# * Best block at time of backup was %i (%s),\n", wallet.GetLastBlockHeight(), wallet.GetLastBlockHash().ToString());
    file << strprintf("#   mined on %s\n", FormatISO8601DateTime(block_time));
    file << "\n";
    // 
    CKeyID seed_id = spk_man.GetHDChain().seed_id;
    if (!seed_id.IsNull())
    {
        CKey seed;
        if (spk_man.GetKey(seed_id, seed)) {
            CExtKey masterKey;
            masterKey.SetSeed(seed);
            file << "# extended private masterkey: " << EncodeExtKey(masterKey) << "\n\n";
        }
    }