minor symfony#14570 [SecurityBundle] Use Enum Nodes Instead Of Scalar (vadim2404)

This PR was merged into the 2.3 branch.

Discussion
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[SecurityBundle] Use Enum Nodes Instead Of Scalar

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | ~
| License       | MIT
| Doc PR        | ~

Commits
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ce7fb04 [SecurityBundle] Use Enum Nodes Instead Of Scalar

Author: Tobion

src/Symfony/Bundle/SecurityBundle/DependencyInjection/MainConfiguration.php

@@ -59,14 +59,14 @@ public function getConfigTreeBuilder()
         $rootNode
             ->children()
                 ->scalarNode('access_denied_url')->defaultNull()->example('/foo/error403')->end()
-                ->scalarNode('session_fixation_strategy')->cannotBeEmpty()->info('strategy can be: none, migrate, invalidate')->defaultValue('migrate')->end()
+                ->enumNode('session_fixation_strategy')->cannotBeEmpty()->values(array('none', 'migrate', 'invalidate'))->defaultValue('migrate')->end()
                 ->booleanNode('hide_user_not_found')->defaultTrue()->end()
                 ->booleanNode('always_authenticate_before_granting')->defaultFalse()->end()
                 ->booleanNode('erase_credentials')->defaultTrue()->end()
                 ->arrayNode('access_decision_manager')
                     ->addDefaultsIfNotSet()
                     ->children()
-                        ->scalarNode('strategy')->defaultValue('affirmative')->end()
+                        ->enumNode('strategy')->values(array('affirmative', 'consensus', 'unanimous'))->defaultValue('affirmative')->end()
                         ->booleanNode('allow_if_all_abstain')->defaultFalse()->end()
                         ->booleanNode('allow_if_equal_granted_denied')->defaultTrue()->end()
                     ->end()