def index
      validate_arguments!

      app_buildpacks = api.get_app_buildpacks_v3(app)[:body]

      if app_buildpacks.nil? or app_buildpacks.empty?
        display("#{app} has no Buildpack URL set.")
      else
        styled_header("#{app} Buildpack URL#{app_buildpacks.size > 1 ? 's' : ''}")
        display_buildpacks(app_buildpacks.map{|bp| bp["buildpack"]["url"]}, "")
      end
    end
def index
      validate_arguments!

      app_buildpacks = api.get_app_buildpacks_v3(app)[:body]

      if app_buildpacks.nil? or app_buildpacks.empty?
        display("#{app} has no Buildpack URL set.")
      else
        styled_header("#{app} Buildpack URL#{app_buildpacks.size > 1 ? 's' : ''}")
        display_buildpacks(app_buildpacks.map{|bp| bp["buildpack"]["url"]}, "")
      end
    end
buildpacks

 display the buildpack_url(s) for an app

Examples:

 $ heroku buildpacks
 https://github.com/heroku/heroku-buildpack-ruby