permit nonce parameter in authorization request

app/controllers/doorkeeper/authorizations_controller.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+require_dependency "#{Doorkeeper::Engine.root}/app/controllers/doorkeeper/authorizations_controller.rb"
+
+module Doorkeeper
+  class AuthorizationsController
+    module AuthorizationsExtension
+      private
+
+      def pre_auth_param_fields
+        super.append(:nonce)
+      end
+    end
+
+    Doorkeeper::AuthorizationsController.send :prepend, AuthorizationsExtension
+  end
+end

spec/controllers/doorkeeper/authorizations_controller_spec.rb

@@ -304,4 +304,11 @@ def reauthenticate!
       end
     end
   end
+
+  describe '#pre_auth' do
+    it 'permits nonce parameter' do
+      authorize! nonce: '123456'
+      expect(assigns(:pre_auth).nonce).to eq '123456'
+    end
+  end
 end