AuthenticateAndRenew.php

<?php

namespace App\Http\Middleware;

use Closure;
use Symfony\Component\HttpKernel\Exception\UnauthorizedHttpException;
use Tymon\JWTAuth\Exceptions\JWTException;
use Tymon\JWTAuth\Http\Middleware\BaseMiddleware;

class AuthenticateAndRenew extends BaseMiddleware
{
    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     *
     * @throws \Symfony\Component\HttpKernel\Exception\UnauthorizedHttpException
     *
     * @return mixed
     */
    public function handle($request, Closure $next)
    {
        $this->checkForToken($request);
        $this->auth->setRefreshFlow();

        try {
            if (! $subject = $this->auth->parseToken()->authenticate()) {
                throw new UnauthorizedHttpException('jwt-auth', 'User not found');
            }
        } catch (JWTException $e) {
            throw new UnauthorizedHttpException('jwt-auth', $e->getMessage(), $e, $e->getCode());
        }

        $response = $next($request);

        return $this->setAuthenticationHeader($response, $this->refreshTokenWithCustomClaims($subject));
    }

    /**
     * Create a refreshed token with updated custom claims.
     *
     * @param  mixed  $subject
     * @return string
     */
    protected function refreshTokenWithCustomClaims($subject)
    {
        return $this->auth->parseToken()->customClaims($subject->fresh()->getJWTCustomClaims())->refresh();
    }
}

and what's the usage of $this->setRefreshFlow() ?