Modernize the style.

lib/src/expiration_exception.dart

Index: lib/src/expiration_exception.dart
diff --git a/lib/src/expiration_exception.dart b/lib/src/expiration_exception.dart
index 9829de1e13017a6252aea4f8ad3e8084594954f4..f684e6ae5a9f53c5b27f2e1999b962ed7391c9f0 100644
--- a/lib/src/expiration_exception.dart
+++ b/lib/src/expiration_exception.dart
@@ -2,7 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library expiration_exception;
+library oauth2.expiration_exception;
 
 import 'credentials.dart';
 
@@ -16,5 +16,5 @@ class ExpirationException implements Exception {
 
   /// Provides a string description of the ExpirationException.
   String toString() =>
-    "OAuth2 credentials have expired and can't be refreshed.";
+      "OAuth2 credentials have expired and can't be refreshed.";
 }