Do not overwrite URL Key with blank value

app/code/Magento/CatalogImportExport/Model/Import/Product.php

@@ -1561,7 +1561,10 @@ protected function _saveProducts()
                 }
                 $rowScope = $this->getRowScope($rowData);
 
-                $rowData[self::URL_KEY] = $this->getUrlKey($rowData);
+                $urlKey = $this->getUrlKey($rowData);
+                if (!empty($urlKey)) {
+                    $rowData[self::URL_KEY] = $urlKey;
+                }
 
                 $rowSku = $rowData[self::COL_SKU];
 
@@ -2406,7 +2409,9 @@ public function validateRow(array $rowData, $rowNum)
      */
     private function isNeedToValidateUrlKey($rowData)
     {
-        return (!empty($rowData[self::URL_KEY]) || !empty($rowData[self::COL_NAME]))
+        $urlKey = $this->getUrlKey($rowData);
+
+        return (!empty($urlKey))
             && (empty($rowData[self::COL_VISIBILITY])
             || $rowData[self::COL_VISIBILITY]
             !== (string)Visibility::getOptionArray()[Visibility::VISIBILITY_NOT_VISIBLE]);
@@ -2718,8 +2723,14 @@ protected function getUrlKey($rowData)
         if (!empty($rowData[self::URL_KEY])) {
             return strtolower($rowData[self::URL_KEY]);
         }
-
-        if (!empty($rowData[self::COL_NAME])) {
+
+        /**
+         * If the product exists, assume it already has a URL Key and even
+         * if a name is provided in the import data, it should not be used
+         * to overwrite that existing URL Key the product already has.
+         */
+        $isSkuExist = $this->isSkuExist($rowData[self::COL_SKU]);
+        if (!$isSkuExist && !empty($rowData[self::COL_NAME])) {
             return $this->productUrl->formatUrlKey($rowData[self::COL_NAME]);
         }
 

dev/tests/integration/testsuite/Magento/CatalogImportExport/Model/Import/ProductTest.php

@@ -1568,15 +1568,20 @@ public function testExistingProductWithUrlKeys()
 
     /**
      * @magentoDataFixture Magento/Catalog/_files/product_simple_with_url_key.php
-     * @magentoDbIsolation disabled
+     * @magentoDbIsolation enabled
      * @magentoAppIsolation enabled
      */
     public function testImportWithoutUrlKeys()
     {
+        /**
+         * Products `simple1` and `simple2` are created by fixture so already
+         * have a URL Key, whereas `new-simple` is a new product so the import
+         * will generate it's URL Key from the name provided in the CSV.
+         */
         $products = [
-            'simple1' => 'simple-1',
-            'simple2' => 'simple-2',
-            'simple3' => 'simple-3'
+            'simple1'    => 'url-key',
+            'simple2'    => 'url-key2',
+            'new-simple' => 'new-simple',
         ];
         $filesystem = $this->objectManager->create(\Magento\Framework\Filesystem::class);
         $directory = $filesystem->getDirectoryWrite(DirectoryList::ROOT);

dev/tests/integration/testsuite/Magento/CatalogImportExport/Model/Import/_files/products_to_import_without_url_keys.csv

@@ -2,3 +2,4 @@ sku,product_type,store_view_code,name,price,attribute_set_code,url_key
 simple1,simple,,"simple 1",25,Default,""
 simple2,simple,,"simple 2",34,Default,""
 simple3,simple,,"simple 3",58,Default,""
+new-simple,simple,,"new simple",25,Default,""