https://travis-ci.org/github/bitcoin/bitcoin/jobs/679885530#L8791
{
public:
    explicit NotificationsHandlerImpl(std::shared_ptr<Chain::Notifications> notifications)
        : m_proxy(std::make_shared<NotificationsProxy>(std::move(notifications)))
    {
        RegisterSharedValidationInterface(m_proxy);
    }
    ~NotificationsHandlerImpl() override { disconnect(); }
    void disconnect() override
    {
        if (m_proxy) {
            UnregisterSharedValidationInterface(m_proxy);
            m_proxy.reset();
        }
    }
    std::shared_ptr<NotificationsProxy> m_proxy;
};
class RpcHandlerImpl : public Handler
{
public:
    explicit RpcHandlerImpl(const CRPCCommand& command) : m_command(command), m_wrapped_command(&command)