protected function getPromiseCorrelationId(Promise $promise)
    {
        $reflectionClass = new \ReflectionClass($promise);
        $reflectionProperty = $reflectionClass->getProperty('receiveCallback');
        $reflectionProperty->setAccessible(true);
        $reflect = new \ReflectionFunction($reflectionProperty->getValue($promise));

        return $reflect->getStaticVariables()['correlationId'];
    }