title: Laravel 6.x new password.confirm middleware doesn't work with custom guard
body: <p>a new password.confirm feature has been added to the laravel 6.2 framework.
  I have a fresh laravel 6.18.8 installation, I have done multi-authentication based on guard.
  I want to run password.confirm for this custom guard.
  Login / logout for guard:admin works correctly, after login redirects to admin/home url correctly. Verification if I am logged in to guard:admin is working correctly so far:
  - if I'm already logged in to guard:admin an attempt to enter admin/login redirects me to admin/home - correctly
  - if I'm not logged in, the attempt to enter admin/home will redirect me to admin/login - correctly</p>
  
  <p>but</p>
  
  <p>trying to go to admin/secret (which should ask for admin password) redirecting me to user login page because to open password/confirm url (for defualt guard)</p>
  
  <p>When I am logged as admin and manually try to open url admin/password/confirm shows error</p>
  
  <pre><code>Target class [admin] does not exist. 
  </code></pre>
  
  <p>Is there any chance to run this? Or is made "as is" and won't play with none default auth guard?</p>
  
  <p>Currently my code for guard:admin:
  <strong>config/auth.php</strong></p>
  
  <pre><code>'guards' =&gt; [
          'web' =&gt; [
              'driver' =&gt; 'session',
              'provider' =&gt; 'users',
          ],
  
          'api' =&gt; [
              'driver' =&gt; 'token',
              'provider' =&gt; 'users',
              'hash' =&gt; false,
          ],
  
          'admin' =&gt; [
              'driver' =&gt; 'session',
              'provider' =&gt; 'admins',
          ],
      ],
  </code></pre>
  
  <p><strong>routes/web.php</strong></p>
  
  <pre><code>/*
  |--------------------------------------------------------------------------
  | Web Routes for admin panel
  |--------------------------------------------------------------------------
  |
  |
  */
  
  Route::prefix( env('ADMIN_PREFIX', 'admin') )-&gt;name('admin.')-&gt;namespace('Admin')-&gt;group(function () {
      // Auth::routes(['register' =&gt; false, 'verify' =&gt; false]);
      // Login/out process
      Route::get('/login', 'Auth\LoginController@showLoginForm')-&gt;name('login');
      Route::post('/login', 'Auth\LoginController@login')-&gt;name('login');
      Route::post('/logout', 'Auth\LoginController@logout')-&gt;name('logout');
      // Password reset process
      Route::get('/password/reset', 'Auth\ForgotPasswordController@showLinkRequestForm')-&gt;name('password.request');
      Route::get('/password/reset/{token}', 'Auth\ResetPasswordController@showResetForm')-&gt;name('password.reset');
      Route::post('/password/email', 'Auth\ForgotPasswordController@sendResetLinkEmail')-&gt;name('password.email');
      Route::post('/password/reset', 'Auth\ResetPasswordController@reset')-&gt;name('password.update');
      // Password confirmation process
      Route::get('/password/confirm', 'Auth\ConfirmPasswordController@showConfirmForm')-&gt;name('password.confirm');
      Route::post('/password/confirm', 'Auth\ConfirmPasswordController@confirm')-&gt;name('password.confirm');
  
      Route::middleware('auth:admin')-&gt;group(function() {
          Route::view('/home', 'admin.home')-&gt;name('home');
          Route::view('/secret', 'admin.secret')-&gt;name('secret')-&gt;middleware('password.confirm');
      });
  </code></pre>