Header name is a string
Header name is a string

- This prevented the confirmation dialog from working:
  https://github.com/heroku/heroku-addon-attachments/issues/25

sancopanco/heroku,greeca0204/heroku,greeca0204/heroku,Faisalawanisee/heroku,vcgato29/heroku,duypq94/heroku,vcgato29/heroku,rkh/heroku,Faisalawanisee/heroku,vcgato29/heroku,gregburek/heroku,Faisalawanisee/heroku,dickeyxxx/heroku,macedo/heroku,duypq94/heroku,gregburek/heroku,duypq94/heroku,rkh/heroku,greeca0204/heroku,dickeyxxx/heroku,dickeyxxx/heroku,sancopanco/heroku,sancopanco/heroku,rkh/heroku,macedo/heroku,gregburek/heroku,macedo/heroku