app_name

# File actionpack/lib/action_dispatch/routing/mapper.rb, line 615
          def app_name(app, rails_app)
            if rails_app
              app.railtie_name
            elsif app.is_a?(Class)
              class_name = app.name
              ActiveSupport::Inflector.underscore(class_name).tr("/", "_")
            end
          end