chore: Resolve merge conflicts

Author: lqiu96

google-auth-library-java/oauth2_http/java/com/google/auth/oauth2/ExternalAccountAuthorizedUserCredentials.java

@@ -94,7 +94,7 @@ public class ExternalAccountAuthorizedUserCredentials extends GoogleCredentials
 
   private @Nullable String refreshToken;
 
-  private transient HttpTransportFactory transportFactory;
+  private transient @Nullable HttpTransportFactory transportFactory;
 
   /**
    * Internal constructor.