Merge pull request #40 from kafene/master

When an optional parameter has no devault value available, set it required

src/Config/Loader/ClassLoader/Resolver/ConstructorResolver.php

@@ -101,7 +101,7 @@ public function getReflected()
     protected function configureOptions(OptionsResolver $optionsResolver)
     {
         foreach ($this->constructorArgs as $name => $param) {
-            if ($param->isOptional()) {
+            if ($param->isOptional() && $param->isDefaultValueAvailable()) {
                 $optionsResolver->setDefault($name, $param->getDefaultValue());
             } else {
                 $optionsResolver->setRequired($name);