fix phpdocs

Admin/FieldDescriptionCollection.php

@@ -45,7 +45,7 @@ class FieldDescriptionCollection implements \ArrayAccess, \Countable
     /**
      * @throws \InvalidArgumentException
      * @param string $name
-     * @return array
+     * @return FieldDescriptionInterface
      */
     public function get($name)
     {

Datagrid/ListMapper.php

@@ -28,6 +28,11 @@ class ListMapper
 
     protected $admin;
 
+    /**
+     * @param \Sonata\AdminBundle\Builder\ListBuilderInterface $listBuilder
+     * @param \Sonata\AdminBundle\Admin\FieldDescriptionCollection $list
+     * @param \Sonata\AdminBundle\Admin\AdminInterface $admin
+     */
     public function __construct(ListBuilderInterface $listBuilder, FieldDescriptionCollection $list, AdminInterface $admin)
     {
         $this->listBuilder  = $listBuilder;
@@ -35,6 +40,12 @@ class ListMapper
         $this->admin        = $admin;
     }
 
+    /**
+     * @param string $name
+     * @param null $type
+     * @param array $fieldDescriptionOptions
+     * @return ListMapper
+     */
     public function addIdentifier($name, $type = null, array $fieldDescriptionOptions = array())
     {
         $fieldDescriptionOptions['identifier'] = true;
@@ -85,7 +96,7 @@ class ListMapper
 
     /**
      * @param string $name
-     * @return array
+     * @return \Sonata\AdminBundle\Admin\FieldDescriptionInterface
      */
     public function get($name)
     {