Merge branch '6.4' into 7.0

* 6.4:
  do not allow version 7 of the HttpKernel component
  favor Twig's include() function over the include tag
  add missing class alias to satisfy autoloading
  remove the .data_collector.command service if its class does not exist
  [HttpFoundation] Add $flush parameter to Response::send()
  fix typo
  DX: PHP CS Fixer - allow for no_superfluous_phpdoc_tags.allow_unused_params

Author: xabbuh

CHANGELOG.md

@@ -19,6 +19,7 @@ CHANGELOG
  * Support root-level `Generator` in `StreamedJsonResponse`
  * Add `UriSigner` from the HttpKernel component
  * Add `partitioned` flag to `Cookie` (CHIPS Cookie)
+ * Add argument `bool $flush = true` to `Response::send()`
 
 6.3
 ---

Response.php

@@ -388,13 +388,20 @@ public function sendContent(): static
     /**
      * Sends HTTP headers and content.
      *
+     * @param bool $flush Whether output buffers should be flushed
+     *
      * @return $this
      */
-    public function send(): static
+    public function send(/* bool $flush = true */): static
     {
         $this->sendHeaders();
         $this->sendContent();
 
+        $flush = 1 <= \func_num_args() ? func_get_arg(0) : true;
+        if (!$flush) {
+            return $this;
+        }
+
         if (\function_exists('fastcgi_finish_request')) {
             fastcgi_finish_request();
         } elseif (\function_exists('litespeed_finish_request')) {