MAGETWO-36625: Extended attributes should be optional

Author: Yu Tang

lib/internal/Magento/Framework/Api/Code/Generator/ExtensionAttributesGenerator.php

@@ -86,7 +86,7 @@ protected function _getClassMethods()
             $methods[] = [
                 'name' => $getterName,
                 'body' => "return \$this->_get('{$attributeName}');",
-                'docblock' => ['tags' => [['name' => 'return', 'description' => $attributeType]]],
+                'docblock' => ['tags' => [['name' => 'return', 'description' => $attributeType . '|null']]],
             ];
             $methods[] = [
                 'name' => $setterName,

lib/internal/Magento/Framework/Api/Test/Unit/Code/Generator/_files/SampleExtension.txt

@@ -6,7 +6,7 @@ namespace Magento\Catalog\Api\Data;
 class ProductExtension extends \Magento\Framework\Api\AbstractSimpleObject implements \Magento\Catalog\Api\Data\ProductExtensionInterface
 {
     /**
-     * @return string
+     * @return string|null
      */
     public function getStringAttribute()
     {
@@ -24,7 +24,7 @@ class ProductExtension extends \Magento\Framework\Api\AbstractSimpleObject imple
     }
 
     /**
-     * @return \Magento\Bundle\Api\Data\OptionInterface[]
+     * @return \Magento\Bundle\Api\Data\OptionInterface[]|null
      */
     public function getComplexObjectAttribute()
     {