Protobuf\Configuration::getInstance PHP Method

    public static function getInstance()
    {
        if (self::$instance !== null) {
            return self::$instance;
        }
        return self::$instance = new Configuration();
    }

 public function testGetConfiguration()
 {
     $config1 = new Configuration();
     $config2 = Configuration::getInstance();
     $serializer1 = new MessageSerializer($config1);
     $serializer2 = new MessageSerializer();
     $this->assertSame($config1, $serializer1->getConfiguration());
     $this->assertSame($config2, $serializer2->getConfiguration());
 }