https://travis-ci.org/github/MarcoFalke/btc_nightly/jobs/680655419#L412
bool SetMaxVersion(int nVersion);
    
    int GetVersion() const { LOCK(cs_wallet); return nWalletVersion; }
    
    std::set<uint256> GetConflicts(const uint256& txid) const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
    
    bool HasWalletSpend(const uint256& txid) const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
    
    void Flush(bool shutdown=false);
    
    boost::signals2::signal<void ()> NotifyUnload;
    /**
     * Address book entry changed.
     * @note called with lock cs_wallet held.
     */
    boost::signals2::signal<void (CWallet *wallet, const CTxDestination
            &address, const std::string &label, bool isMine,
            const std::string &purpose,
            ChangeType status)> NotifyAddressBookChanged;
    /**
     * Wallet transaction added, removed or updated.
     * @note called with lock cs_wallet held.
     */
    boost::signals2::signal<void (CWallet *wallet, const uint256 &hashTx,
            ChangeType status)> NotifyTransactionChanged;