all: fix some comments

Change-Id: I3dd3785de7071e34320a148f35d4caa97cfd6db1
Reviewed-on: https://go-review.googlesource.com/c/oauth2/+/713361
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Sean Liao <sean@liao.dev>
Auto-Submit: Sean Liao <sean@liao.dev>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>

Author: cuishuang

clientcredentials/clientcredentials.go

@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // Package clientcredentials implements the OAuth2.0 "client credentials" token flow,
-// also known as the "two-legged OAuth 2.0".
+// also known as "two-legged OAuth 2.0".
 //
 // This should be used when the client is acting on its own behalf or when the client
 // is the resource owner. It may also be used when requesting access to protected

google/google.go

@@ -252,7 +252,7 @@ func (f *credentialsFile) tokenSource(ctx context.Context, params CredentialsPar
 // Further information about retrieving access tokens from the GCE metadata
 // server can be found at https://cloud.google.com/compute/docs/authentication.
 func ComputeTokenSource(account string, scope ...string) oauth2.TokenSource {
-	// refresh 3 minutes and 45 seconds early. The shortest MDS cache is currently 4 minutes, so any
+	// Refresh 3 minutes and 45 seconds early. The shortest MDS cache is currently 4 minutes, so any
 	// refreshes earlier are a waste of compute.
 	earlyExpirySecs := 225 * time.Second
 	return computeTokenSource(account, earlyExpirySecs, scope...)

oauth2.go

@@ -98,7 +98,7 @@ const (
 	// in the POST body as application/x-www-form-urlencoded parameters.
 	AuthStyleInParams AuthStyle = 1
 
-	// AuthStyleInHeader sends the client_id and client_password
+	// AuthStyleInHeader sends the client_id and client_secret
 	// using HTTP Basic Authorization. This is an optional style
 	// described in the OAuth2 RFC 6749 section 2.3.1.
 	AuthStyleInHeader AuthStyle = 2

pkce.go

@@ -51,7 +51,7 @@ func S256ChallengeFromVerifier(verifier string) string {
 	return base64.RawURLEncoding.EncodeToString(sha[:])
 }
 
-// S256ChallengeOption derives a PKCE code challenge derived from verifier with
+// S256ChallengeOption derives a PKCE code challenge from the verifier with
 // method S256. It should be passed to [Config.AuthCodeURL] or [Config.DeviceAuth]
 // only.
 func S256ChallengeOption(verifier string) AuthCodeOption {

token.go

@@ -103,7 +103,7 @@ func (t *Token) WithExtra(extra any) *Token {
 }
 
 // Extra returns an extra field.
-// Extra fields are key-value pairs returned by the server as a
+// Extra fields are key-value pairs returned by the server as
 // part of the token retrieval response.
 func (t *Token) Extra(key string) any {
 	if raw, ok := t.raw.(map[string]any); ok {

transport.go

@@ -58,7 +58,7 @@ func (t *Transport) RoundTrip(req *http.Request) (*http.Response, error) {
 var cancelOnce sync.Once
 
 // CancelRequest does nothing. It used to be a legacy cancellation mechanism
-// but now only it only logs on first use to warn that it's deprecated.
+// but now only logs on first use to warn that it's deprecated.
 //
 // Deprecated: use contexts for cancellation instead.
 func (t *Transport) CancelRequest(req *http.Request) {