[Config] fix return type declarations

Author: derrabus

Definition/ArrayNode.php

@@ -38,17 +38,13 @@ public function setNormalizeKeys($normalizeKeys)
     }
 
     /**
-     * Normalizes keys between the different configuration formats.
+     * {@inheritdoc}
      *
      * Namely, you mostly have foo_bar in YAML while you have foo-bar in XML.
      * After running this method, all keys are normalized to foo_bar.
      *
      * If you have a mixed key like foo-bar_moo, it will not be altered.
      * The key will also not be altered if the target key already exists.
-     *
-     * @param mixed $value
-     *
-     * @return array The value with normalized keys
      */
     protected function preNormalize($value)
     {

Definition/BaseNode.php

@@ -49,21 +49,37 @@ public function __construct($name, NodeInterface $parent = null)
         $this->parent = $parent;
     }
 
+    /**
+     * @param string $key
+     */
     public function setAttribute($key, $value)
     {
         $this->attributes[$key] = $value;
     }
 
+    /**
+     * @param string $key
+     *
+     * @return mixed
+     */
     public function getAttribute($key, $default = null)
     {
         return isset($this->attributes[$key]) ? $this->attributes[$key] : $default;
     }
 
+    /**
+     * @param string $key
+     *
+     * @return bool
+     */
     public function hasAttribute($key)
     {
         return isset($this->attributes[$key]);
     }
 
+    /**
+     * @return array
+     */
     public function getAttributes()
     {
         return $this->attributes;
@@ -74,6 +90,9 @@ public function setAttributes(array $attributes)
         $this->attributes = $attributes;
     }
 
+    /**
+     * @param string $key
+     */
     public function removeAttribute($key)
     {
         unset($this->attributes[$key]);
@@ -92,7 +111,7 @@ public function setInfo($info)
     /**
      * Returns info message.
      *
-     * @return string The info text
+     * @return string|null The info text
      */
     public function getInfo()
     {
@@ -112,7 +131,7 @@ public function setExample($example)
     /**
      * Retrieves the example configuration for this node.
      *
-     * @return string|array The example
+     * @return string|array|null The example
      */
     public function getExample()
     {

Definition/PrototypedArrayNode.php

@@ -78,7 +78,7 @@ public function setKeyAttribute($attribute, $remove = true)
     /**
      * Retrieves the name of the attribute which value should be used as key.
      *
-     * @return string The name of the attribute
+     * @return string|null The name of the attribute
      */
     public function getKeyAttribute()
     {

Util/XmlUtils.php

@@ -152,7 +152,7 @@ public static function loadFile($file, $schemaOrCallable = null)
      * @param \DOMElement $element     A \DOMElement instance
      * @param bool        $checkPrefix Check prefix in an element or an attribute name
      *
-     * @return array A PHP array
+     * @return mixed
      */
     public static function convertDomElementToArray(\DOMElement $element, $checkPrefix = true)
     {