chore: use credential-specific fromStream method (#2242)

Author: diegomarquezp

src/test/java/com/google/cloud/spanner/jdbc/JdbcDatabaseMetaDataTest.java

@@ -23,7 +23,7 @@
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
-import com.google.auth.oauth2.GoogleCredentials;
+import com.google.auth.oauth2.ServiceAccountCredentials;
 import com.google.cloud.spanner.Dialect;
 import com.google.cloud.spanner.connection.ConnectionOptions;
 import com.google.cloud.spanner.connection.ConnectionOptionsTest;
@@ -555,8 +555,8 @@ public void testGetVersionColumns() throws SQLException {
 
   @Test
   public void testGetUserName() throws SQLException, IOException {
-    GoogleCredentials credentials =
-        GoogleCredentials.fromStream(
+    ServiceAccountCredentials credentials =
+        ServiceAccountCredentials.fromStream(
             Objects.requireNonNull(ConnectionOptionsTest.class.getResource("test-key.json"))
                 .openStream());
     JdbcConnection connection = mock(JdbcConnection.class);

src/test/java/com/google/cloud/spanner/jdbc/it/ITJdbcConnectTest.java

@@ -20,6 +20,7 @@
 
 import com.google.auth.oauth2.AccessToken;
 import com.google.auth.oauth2.GoogleCredentials;
+import com.google.auth.oauth2.ServiceAccountCredentials;
 import com.google.cloud.spanner.Database;
 import com.google.cloud.spanner.Dialect;
 import com.google.cloud.spanner.ParallelIntegrationTest;
@@ -230,7 +231,8 @@ public void testConnectWithDataSourceWithConflictingValues() throws SQLException
   public void testConnectWithOAuthToken() throws Exception {
     GoogleCredentials credentials;
     if (hasValidKeyFile()) {
-      credentials = GoogleCredentials.fromStream(Files.newInputStream(Paths.get(getKeyFile())));
+      credentials =
+          ServiceAccountCredentials.fromStream(Files.newInputStream(Paths.get(getKeyFile())));
     } else {
       try {
         credentials = GoogleCredentials.getApplicationDefault();