MAGETWO-58383: [Backport] - [GitHub] Saving CMS page does not create URL rewrite in Magento 2.1.0 with single-store mode #5923 - for 2.1

Author: StasKozar

dev/tests/functional/tests/app/Magento/Cms/Test/Constraint/AssertCmsPageOnFrontend.php

@@ -21,7 +21,7 @@ class AssertCmsPageOnFrontend extends AbstractConstraint
      * @param CmsPage $cms
      * @param FrontCmsPage $frontCmsPage,
      * @param BrowserInterface $browser
-     * @param string $displayContent
+     * @param string|null $displayContent
      * @return void
      */
     public function processAssert(