@jonasschnelli wrote in #14979:
> #14573 broke < Qt5.6 compatibility due to calling the lambda version of `addAction` that was added in Qt5.6.

We currently [support](https://github.com/bitcoin/bitcoin/blob/master/doc/dependencies.md) QT >=5.2, but hardly anyone tests with that. If we make one of the Travis machines use it, we should have a better change of catching this.

See also discussion about minimum QT version in #13478 
bool setAddressBook(const CTxDestination& dest, const std::string& name, const std::string& purpose) override
    {
        return m_wallet.SetAddressBook(dest, name, purpose);
    }
    bool delAddressBook(const CTxDestination& dest) override
    {
        return m_wallet.DelAddressBook(dest);
    }
    bool getAddress(const CTxDestination& dest,
        std::string* name,
        isminetype* is_mine,
        std::string* purpose) override
    {
        LOCK(m_wallet.cs_wallet);
        auto it = m_wallet.mapAddressBook.find(dest);
        if (it == m_wallet.mapAddressBook.end()) {
            return false;
        }
        if (name) {
            *name = it->second.name;
        }
        if (is_mine) {
            *is_mine = IsMine(m_wallet, dest);
        }
        if (purpose) {
            *purpose = it->second.purpose;
        }
        return true;
    }
    std::vector<WalletAddress> getAddresses() override