It's currently not possible to import (solvable) SegWit addresses (P2SH and native) using `importmulti`. I believe that's a shortcoming we should address before release.

My suggestion would be for P2WPKH (P2SH and native) to be supported without any extra arguments. This means that a P2WPKH address/script with corresponding private or public key should work. For P2SH it means checking if the supplied P2SH address perhaps matches the supplied public key or private key when converted to P2WPKH first.

To support P2WSH, I think we need an extra field "witnessScript". When supplied, it would either be required to match a P2WSH address/script directly, or if the address is P2SH, indirectly.
+ HelpExampleRpc("walletlock", "")
        );
    }
    LOCK2(cs_main, pwallet->cs_wallet);
    if (!pwallet->IsCrypted()) {
        throw JSONRPCError(RPC_WALLET_WRONG_ENC_STATE, "Error: running with an unencrypted wallet, but walletlock was called.");
    }
    pwallet->Lock();
    pwallet->nRelockTime = 0;
    return NullUniValue;
}
static UniValue encryptwallet(const JSONRPCRequest& request)
{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    CWallet* const pwallet = wallet.get();
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
        return NullUniValue;
    }
    if (request.fHelp || request.params.size() != 1) {
        throw std::runtime_error(
            "encryptwallet \"passphrase\"\n"
            "\nEncrypts the wallet with 'passphrase'. This is for first time encryption.\n"
            "After this, any calls that interact with private keys such as sending or signing \n"
            "will require the passphrase to be set prior the making these calls.\n"
            "Use the walletpassphrase call for this, and then walletlock call.\n"
            "If the wallet is already encrypted, use the walletpassphrasechange call.\n"
            "\nArguments:\n"
            "1. \"passphrase\"    (string) The pass phrase to encrypt the wallet with. It must be at least 1 character, but should be long.\n"
            "\nExamples:\n"
            "\nEncrypt your wallet\n"