Adds TokenSourceWithOptions to refresh token that allows for setting additional attributes

- Support for rfc 7523 in refresh token

Author: sks

oauth2.go

@@ -242,14 +242,14 @@ func (c *Config) Client(ctx context.Context, t *Token) *http.Client {
 	return NewClient(ctx, c.TokenSource(ctx, t))
 }
 
-// TokenSource returns a [TokenSource] that returns t until t expires,
-// automatically refreshing it as necessary using the provided context.
+// TokenSourceWithOptions returns a [TokenSource] that returns t until t expires,
 //
-// Most users will use [Config.Client] instead.
-func (c *Config) TokenSource(ctx context.Context, t *Token) TokenSource {
+// This method provides a way to pass options to the token source.
+func (c *Config) TokenSourceWithOptions(ctx context.Context, t *Token, opts ...AuthCodeOption) TokenSource {
 	tkr := &tokenRefresher{
 		ctx:  ctx,
 		conf: c,
+		opts: opts,
 	}
 	if t != nil {
 		tkr.refreshToken = t.RefreshToken
@@ -260,12 +260,21 @@ func (c *Config) TokenSource(ctx context.Context, t *Token) TokenSource {
 	}
 }
 
+// TokenSource returns a [TokenSource] that returns t until t expires,
+// automatically refreshing it as necessary using the provided context.
+//
+// Most users will use [Config.Client] instead.
+func (c *Config) TokenSource(ctx context.Context, t *Token) TokenSource {
+	return c.TokenSourceWithOptions(ctx, t)
+}
+
 // tokenRefresher is a TokenSource that makes "grant_type=refresh_token"
 // HTTP requests to renew a token using a RefreshToken.
 type tokenRefresher struct {
 	ctx          context.Context // used to get HTTP requests
 	conf         *Config
 	refreshToken string
+	opts         []AuthCodeOption
 }
 
 // WARNING: Token is not safe for concurrent access, as it
@@ -277,10 +286,15 @@ func (tf *tokenRefresher) Token() (*Token, error) {
 		return nil, errors.New("oauth2: token expired and refresh token is not set")
 	}
 
-	tk, err := retrieveToken(tf.ctx, tf.conf, url.Values{
+	v := url.Values{
 		"grant_type":    {"refresh_token"},
 		"refresh_token": {tf.refreshToken},
-	})
+	}
+	for _, opt := range tf.opts {
+		opt.setValue(v)
+	}
+
+	tk, err := retrieveToken(tf.ctx, tf.conf, v)
 
 	if err != nil {
 		return nil, err

oauth2_test.go

@@ -551,6 +551,32 @@ func TestRefreshToken_RefreshTokenReplacement(t *testing.T) {
 	}
 }
 
+func TestRefreshToken_RefreshWithOpts(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		body, err := io.ReadAll(r.Body)
+		if err != nil {
+			t.Errorf("Failed reading request body: %s.", err)
+		}
+		if string(body) != "foo=bar&grant_type=refresh_token&refresh_token=OLD_REFRESH_TOKEN" {
+			t.Errorf("Unexpected exchange payload; got %q", body)
+		}
+		w.Header().Set("Content-Type", "application/json")
+		w.Write([]byte(`{"access_token":"ACCESS_TOKEN",  "scope": "user", "token_type": "bearer", "refresh_token": "NEW_REFRESH_TOKEN"}`))
+		return
+	}))
+	defer ts.Close()
+	conf := newConf(ts.URL)
+	tkr := conf.TokenSourceWithOptions(context.Background(), &Token{RefreshToken: "OLD_REFRESH_TOKEN"}, SetAuthURLParam("foo", "bar"))
+	tk, err := tkr.Token()
+	if err != nil {
+		t.Errorf("got err = %v; want none", err)
+		return
+	}
+	if want := "NEW_REFRESH_TOKEN"; tk.RefreshToken != want {
+		t.Errorf("RefreshToken = %q; want %q", tk.RefreshToken, want)
+	}
+}
+
 func TestRefreshToken_RefreshTokenPreservation(t *testing.T) {
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Content-Type", "application/json")