Switched ObjectManager dependency to be declared as interface rather than concrete class

Author: Allan Paiste

app/code/Magento/Catalog/Model/Category/Attribute/Backend/Image.php

@@ -49,20 +49,21 @@ class Image extends \Magento\Eav\Model\Entity\Attribute\Backend\AbstractBackend
     private $imageUploader;
 
     /**
-     * @var \Magento\Framework\App\ObjectManager
+     * @var \Magento\Framework\ObjectManagerInterface
      */
     private $objectManager;
 
     /**
      * @param \Psr\Log\LoggerInterface $logger
      * @param \Magento\Framework\Filesystem $filesystem
      * @param \Magento\MediaStorage\Model\File\UploaderFactory $fileUploaderFactory
+     * @param \Magento\Framework\ObjectManagerInterface
      */
     public function __construct(
         \Psr\Log\LoggerInterface $logger,
         \Magento\Framework\Filesystem $filesystem,
         \Magento\MediaStorage\Model\File\UploaderFactory $fileUploaderFactory,
-        \Magento\Framework\App\ObjectManager $objectManager
+        \Magento\Framework\ObjectManagerInterface $objectManager
     ) {
         $this->_filesystem = $filesystem;
         $this->_fileUploaderFactory = $fileUploaderFactory;