⏫ Forwardport of #12003 to 2.3-develop branch

Applied pull request patch https://github.com/magento/magento2/pull/12003.patch (created by @p-bystritsky) based on commit(s):
  1. bd9054a

Fixed GitHub Issues in 2.3-develop branch:
  - #11691: Wrong return type for getAttributeText($attributeCode) (reported by @diazwatson)

Author: magento-engcom-team

app/code/Magento/Catalog/Model/Product.php

@@ -1712,7 +1712,7 @@ public function isInStock()
      * Get attribute text by its code
      *
      * @param string $attributeCode Code of the attribute
-     * @return string
+     * @return string|array|null
      */
     public function getAttributeText($attributeCode)
     {

dev/tests/integration/testsuite/Magento/Catalog/Model/ProductGettersTest.php

@@ -5,6 +5,7 @@
  */
 namespace Magento\Catalog\Model;
 
+use Magento\Catalog\Api\ProductRepositoryInterface;
 use Magento\Framework\App\Filesystem\DirectoryList;
 
 /**
@@ -25,11 +26,19 @@ class ProductGettersTest extends \PHPUnit\Framework\TestCase
      */
     protected $_model;
 
+    /**
+     * @var ProductRepositoryInterface
+     */
+    private $productRepository;
+
     protected function setUp()
     {
         $this->_model = \Magento\TestFramework\Helper\Bootstrap::getObjectManager()->create(
             \Magento\Catalog\Model\Product::class
         );
+        $this->productRepository = \Magento\TestFramework\Helper\Bootstrap::getObjectManager()->create(
+            ProductRepositoryInterface::class
+        );
     }
 
     public function testGetResourceCollection()
@@ -198,6 +207,24 @@ public function testGetAttributeText()
         $this->assertEquals('Enabled', $this->_model->getAttributeText('status'));
     }
 
+    /**
+     * @magentoDataFixture Magento/Catalog/_files/products_with_multiselect_attribute.php
+     */
+    public function testGetAttributeTextArray()
+    {
+        $product = $this->productRepository->get('simple_ms_2');
+        $product->getAttributeText('multiselect_attribute');
+        $expected = [
+            'Option 2',
+            'Option 3',
+            'Option 4 "!@#$%^&*'
+        ];
+        self::assertEquals(
+            $expected,
+            $product->getAttributeText('multiselect_attribute')
+        );
+    }
+
     public function testGetCustomDesignDate()
     {
         $this->assertEquals(['from' => null, 'to' => null], $this->_model->getCustomDesignDate());