Fix some phpdoc

Author: alamirault

Tests/Fixtures/MockStream/MockStream.php

@@ -22,11 +22,11 @@ class MockStream
     /**
      * Opens file or URL.
      *
-     * @param string $path        Specifies the URL that was passed to the original function
-     * @param string $mode        The mode used to open the file, as detailed for fopen()
-     * @param int    $options     Holds additional flags set by the streams API
-     * @param string $opened_path If the path is opened successfully, and STREAM_USE_PATH is set in options,
-     *                            opened_path should be set to the full path of the file/resource that was actually opened
+     * @param string      $path        Specifies the URL that was passed to the original function
+     * @param string      $mode        The mode used to open the file, as detailed for fopen()
+     * @param int         $options     Holds additional flags set by the streams API
+     * @param string|null $opened_path If the path is opened successfully, and STREAM_USE_PATH is set in options,
+     *                                 opened_path should be set to the full path of the file/resource that was actually opened
      */
     public function stream_open(string $path, string $mode, int $options, string &$opened_path = null): bool
     {