使用composer autoload.php加载自定义类时出错

I'm trying to load a custom class (google_auth.class.php) with the composer autoload.

This is my structure file:

/vendor
/lib/src/google_auth.class.php
index.php
autoload.php';

this is autoload.php

<?php
  return require __DIR__ . '/vendor/autoload.php';
?>

This is my index.php code:

<?php
$autoloader = require_once 'autoload.php';
require_once 'init.php';
$googleClient = new Google_Client();
$auth = new GoogleOauthClass($googleClient);
?>

I add this code to my composer.json:

"autoload":{
  "psr-4":{
    "GoogleOauth\\": "lib/src/"
  }
}

And run composer dump-autoload

If I execute: php index.php I get this message:

PHP Fatal error:  Class 'GoogleOauthClass' not found in /home/oskar/webapps/sourcecode/googlelogin/index.php on line 19

If I add to the files this line:

 require_once ('lib/src/google_auth.class.php');

It works fine.

Thanks.

Oskar