// constructor for unit testing purposes
 internal Downloader(BlockchainTransactionService blockchainTransactionService,
                     RetrieveProximaxMessagePayloadService retrieveProximaxMessagePayloadService,
                     RetrieveProximaxDataService retrieveProximaxDataService)
 {
     BlockchainTransactionService          = blockchainTransactionService;
     RetrieveProximaxMessagePayloadService = retrieveProximaxMessagePayloadService;
     RetrieveProximaxDataService           = retrieveProximaxDataService;
 }
 public Downloader(ConnectionConfig connectionConfig)
 {
     RetrieveProximaxMessagePayloadService =
         new RetrieveProximaxMessagePayloadService(connectionConfig.BlockchainNetworkConnection);
     RetrieveProximaxDataService  = new RetrieveProximaxDataService(connectionConfig.FileStorageConnection);
     BlockchainTransactionService =
         new BlockchainTransactionService(connectionConfig.BlockchainNetworkConnection);
 }