Clarify that client credentials are not passed in the URL

The term "query parameters" suggested that the credentials are passed in the URL which is insecure and is actually not true as the credentials are passed in the request body. See

Change-Id: Id0a83f8d317fed30e18310b30860000109dafe88
GitHub-Last-Rev: 3961bc9affcbdb16a6e0b4db58ce0526da8e728b
GitHub-Pull-Request: golang/oauth2#358
Reviewed-by: Brad Fitzpatrick <>
diff --git a/oauth2.go b/oauth2.go
index 1e8e1b7..3de6331 100644
--- a/oauth2.go
+++ b/oauth2.go
@@ -31,7 +31,7 @@
 // which doesn't support the HTTP Basic authentication
 // scheme to authenticate with the authorization server.
 // Once a server is registered, credentials (client_id and client_secret)
-// will be passed as query parameters rather than being present
+// will be passed as parameters in the request body rather than being present
 // in the Authorization header.
 // See for background.
 func RegisterBrokenAuthHeaderProvider(tokenURL string) {