forms: consider empty input as default choice on optional prompt
forms: consider empty input as default choice on optional prompt

dr-em/BotBuilder,Clairety/ConnectMe,yakumo/BotBuilder,jockorob/BotBuilder,digibaraka/BotBuilder,jockorob/BotBuilder,navaei/BotBuilder,msft-shahins/BotBuilder,stevengum97/BotBuilder,mmatkow/BotBuilder,msft-shahins/BotBuilder,Clairety/ConnectMe,digibaraka/BotBuilder,digibaraka/BotBuilder,xiangyan99/BotBuilder,mmatkow/BotBuilder,mmatkow/BotBuilder,stevengum97/BotBuilder,msft-shahins/BotBuilder,navaei/BotBuilder,navaei/BotBuilder,navaei/BotBuilder,stevengum97/BotBuilder,msft-shahins/BotBuilder,stevengum97/BotBuilder,xiangyan99/BotBuilder,xiangyan99/BotBuilder,dr-em/BotBuilder,jockorob/BotBuilder,Clairety/ConnectMe,digibaraka/BotBuilder,dr-em/BotBuilder,yakumo/BotBuilder,yakumo/BotBuilder,dr-em/BotBuilder,mmatkow/BotBuilder,xiangyan99/BotBuilder,jockorob/BotBuilder,Clairety/ConnectMe,yakumo/BotBuilder