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src/DependencyInjection/Configuration.php

@@ -61,7 +61,7 @@ class Configuration implements ConfigurationInterface
                     ->end()
 
                     ->arrayPrototype()
-                        ->normalizeKeys(false)
+                        ->normalizeKeys(false) # Don't normalize hyphens into underscores etc
                         ->children()
                             ->scalarNode('fill')->isRequired()->end()
                             ->scalarNode('stroke')->isRequired()->end()