OAuth2\OAuth2::getBearerTokenFromHeaders PHP Method

    protected function getBearerTokenFromHeaders(Request $request, $removeFromRequest)
    {
        $header = null;
        if (!$request->headers->has('AUTHORIZATION')) {
            // The Authorization header may not be passed to PHP by Apache;
            // Trying to obtain it through apache_request_headers()
            if (function_exists('apache_request_headers')) {
                $headers = apache_request_headers();
                if (is_array($headers)) {
                    // Server-side fix for bug in old Android versions (a nice side-effect of this fix means we don't care about capitalization for Authorization)
                    $headers = array_combine(array_map('ucwords', array_keys($headers)), array_values($headers));
                    if (isset($headers['Authorization'])) {
                        $header = $headers['Authorization'];
                    }
                }
            }
        } else {
            $header = $request->headers->get('AUTHORIZATION');
        }
        if (!$header) {
            return null;
        }
        if (!preg_match('/' . preg_quote(self::TOKEN_BEARER_HEADER_NAME, '/') . '\\s(\\S+)/', $header, $matches)) {
            return null;
        }
        $token = $matches[1];
        if ($removeFromRequest) {
            $request->headers->remove('AUTHORIZATION');
        }
        return $token;
    }