https://travis-ci.org/github/bitcoin/bitcoin/jobs/679885530#L8791
virtual CFeeRate relayDustFee() = 0;
    
    virtual bool havePruned() = 0;
    
    virtual bool isReadyToBroadcast() = 0;
    
    virtual bool isInitialBlockDownload() = 0;
    
    virtual bool shutdownRequested() = 0;
    
    virtual int64_t getAdjustedTime() = 0;
    
    virtual void initMessage(const std::string& message) = 0;
    
    virtual void initWarning(const bilingual_str& message) = 0;
    
    virtual void initError(const bilingual_str& message) = 0;
    
    virtual void showProgress(const std::string& title, int progress, bool resume_possible) = 0;
    
    class Notifications
    {
    public:
        virtual ~Notifications() {}
        virtual void transactionAddedToMempool(const CTransactionRef& tx, uint64_t mempool_sequence) {}
        virtual void transactionRemovedFromMempool(const CTransactionRef& tx, MemPoolRemovalReason reason, uint64_t mempool_sequence) {}
        virtual void blockConnected(const CBlock& block, int height) {}
        virtual void blockDisconnected(const CBlock& block, int height) {}
        virtual void updatedBlockTip() {}
        virtual void chainStateFlushed(const CBlockLocator& locator) {}