merged branch elnur/interface-public-modifier (PR #7397)

This PR was submitted for the 2.0 branch but it was merged into the 2.1 branch instead (closes #7397).

Commits
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8ee05e5 Add a public modifier to an interface method

Discussion
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[2.0][Security] Add a public modifier to an interface method

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes

src/Symfony/Component/Security/Core/Authentication/Provider/AuthenticationProviderInterface.php

@@ -31,5 +31,5 @@ interface AuthenticationProviderInterface extends AuthenticationManagerInterface
      *
      * @return Boolean true if the implementation supports the Token, false otherwise
      */
-     function supports(TokenInterface $token);
+     public function supports(TokenInterface $token);
 }