fix: respect token_uri from json in UserCredentials creation. (#1630)

* fix: respect token_uri from json in UserCredentials creation.

* fix format

* add comment.

Author: zhumin8

oauth2_http/java/com/google/auth/oauth2/UserCredentials.java

@@ -124,13 +124,16 @@ static UserCredentials fromJson(Map<String, Object> json, HttpTransportFactory t
           "Error reading user credential from JSON, "
               + " expecting 'client_id', 'client_secret' and 'refresh_token'.");
     }
+    // currently "token_uri" is not a default field and needs to be added to json file manually
+    String tokenUrl = (String) json.get("token_uri");
+    URI tokenUri = (tokenUrl == null || tokenUrl.isEmpty()) ? null : URI.create(tokenUrl);
     return UserCredentials.newBuilder()
         .setClientId(clientId)
         .setClientSecret(clientSecret)
         .setRefreshToken(refreshToken)
         .setAccessToken(null)
         .setHttpTransportFactory(transportFactory)
-        .setTokenServerUri(null)
+        .setTokenServerUri(tokenUri)
         .setQuotaProjectId(quotaProjectId)
         .build();
   }

oauth2_http/javatests/com/google/auth/oauth2/UserCredentialsTest.java

@@ -131,20 +131,44 @@ public void fromJson_hasAccessToken() throws IOException {
     MockTokenServerTransportFactory transportFactory = new MockTokenServerTransportFactory();
     transportFactory.transport.addClient(CLIENT_ID, CLIENT_SECRET);
     transportFactory.transport.addRefreshToken(REFRESH_TOKEN, ACCESS_TOKEN);
-    GenericJson json = writeUserJson(CLIENT_ID, CLIENT_SECRET, REFRESH_TOKEN, null);
+    GenericJson json = writeUserJson(CLIENT_ID, CLIENT_SECRET, REFRESH_TOKEN, null, null);
 
     GoogleCredentials credentials = UserCredentials.fromJson(json, transportFactory);
 
     Map<String, List<String>> metadata = credentials.getRequestMetadata(CALL_URI);
     TestUtils.assertContainsBearerToken(metadata, ACCESS_TOKEN);
   }
 
+  @Test
+  public void fromJson_hasTokenUri() throws IOException {
+    String tokenUrl = "token.url.xyz";
+    MockTokenServerTransportFactory transportFactory = new MockTokenServerTransportFactory();
+    transportFactory.transport.addClient(CLIENT_ID, CLIENT_SECRET);
+    transportFactory.transport.addRefreshToken(REFRESH_TOKEN, ACCESS_TOKEN);
+    GenericJson json = writeUserJson(CLIENT_ID, CLIENT_SECRET, REFRESH_TOKEN, null, tokenUrl);
+
+    UserCredentials credentials = UserCredentials.fromJson(json, transportFactory);
+    assertEquals(URI.create(tokenUrl), credentials.toBuilder().getTokenServerUri());
+  }
+
+  @Test
+  public void fromJson_emptyTokenUri() throws IOException {
+    String tokenUrl = "";
+    MockTokenServerTransportFactory transportFactory = new MockTokenServerTransportFactory();
+    transportFactory.transport.addClient(CLIENT_ID, CLIENT_SECRET);
+    transportFactory.transport.addRefreshToken(REFRESH_TOKEN, ACCESS_TOKEN);
+    GenericJson json = writeUserJson(CLIENT_ID, CLIENT_SECRET, REFRESH_TOKEN, null, tokenUrl);
+
+    UserCredentials credentials = UserCredentials.fromJson(json, transportFactory);
+    assertEquals(OAuth2Utils.TOKEN_SERVER_URI, credentials.toBuilder().getTokenServerUri());
+  }
+
   @Test
   public void fromJson_hasQuotaProjectId() throws IOException {
     MockTokenServerTransportFactory transportFactory = new MockTokenServerTransportFactory();
     transportFactory.transport.addClient(CLIENT_ID, CLIENT_SECRET);
     transportFactory.transport.addRefreshToken(REFRESH_TOKEN, ACCESS_TOKEN);
-    GenericJson json = writeUserJson(CLIENT_ID, CLIENT_SECRET, REFRESH_TOKEN, QUOTA_PROJECT);
+    GenericJson json = writeUserJson(CLIENT_ID, CLIENT_SECRET, REFRESH_TOKEN, QUOTA_PROJECT, null);
 
     GoogleCredentials credentials = UserCredentials.fromJson(json, transportFactory);
 
@@ -865,7 +889,11 @@ public void userCredentials_toBuilder_copyEveryAttribute() {
   }
 
   static GenericJson writeUserJson(
-      String clientId, String clientSecret, String refreshToken, String quotaProjectId) {
+      String clientId,
+      String clientSecret,
+      String refreshToken,
+      String quotaProjectId,
+      String tokenUrl) {
     GenericJson json = new GenericJson();
     if (clientId != null) {
       json.put("client_id", clientId);
@@ -879,14 +907,17 @@ static GenericJson writeUserJson(
     if (quotaProjectId != null) {
       json.put("quota_project_id", quotaProjectId);
     }
+    if (tokenUrl != null) {
+      json.put("token_uri", tokenUrl);
+    }
     json.put("type", GoogleCredentials.USER_FILE_TYPE);
     return json;
   }
 
   static InputStream writeUserStream(
       String clientId, String clientSecret, String refreshToken, String quotaProjectId)
       throws IOException {
-    GenericJson json = writeUserJson(clientId, clientSecret, refreshToken, quotaProjectId);
+    GenericJson json = writeUserJson(clientId, clientSecret, refreshToken, quotaProjectId, null);
     return TestUtils.jsonToInputStream(json);
   }