downscope: update documentation

google/downscope/example_test.go

@@ -6,11 +6,16 @@ package downscope_test
 
 import (
 	"context"
+	"fmt"
 
 	"golang.org/x/oauth2"
 	"golang.org/x/oauth2/google/downscope"
 )
 
+func Example() {
+
+}
+
 func ExampleNewTokenSource() {
 	ctx := context.Background()
 	// Initializes an accessBoundary with one Rule.
@@ -29,8 +34,12 @@ func ExampleNewTokenSource() {
 
 	dts, err := downscope.NewTokenSource(ctx, downscope.DownscopingConfig{RootSource: rootSource, Rules: accessBoundary})
 	if err != nil {
-		_ = dts
+		fmt.Printf("failed to generate downscoped token source: %v", err)
 	}
+
+	// Enables automatic token refreshing
+	_ := oauth2.ReuseTokenSource(nil, dts)
+
 	// You can now use the token held in myTokenSource to make
 	// Google Cloud Storage calls, as follows: