bug symfony#8519 Improved the first example of the Guard authenticator (javiereguiluz)

This PR was merged into the 3.4 branch.

Discussion
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Improved the first example of the Guard authenticator

I don't like the changes I made to this example in symfony#8497. I consider that the new version of the example makes more sense and it's more correct.

Commits
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ad84f23 Improved the first example of the Guard authenticator

Author: weaverryan

security/guard_authentication.rst

@@ -171,23 +171,17 @@ This requires you to implement several methods::
          */
         public function supports(Request $request)
         {
-            return true;
+            return $request->headers->has('X-AUTH-TOKEN')
         }
 
         /**
          * Called on every request. Return whatever credentials you want to
-         * be passed to getUser().
+         * be passed to getUser() as $credentials.
          */
         public function getCredentials(Request $request)
         {
-            if (!$token = $request->headers->get('X-AUTH-TOKEN')) {
-                // No token?
-                $token = null;
-            }
-
-            // What you return here will be passed to getUser() as $credentials
             return array(
-                'token' => $token,
+                'token' => $request->headers->get('X-AUTH-TOKEN'),
             );
         }