[TASK] Mark OutputFormatter as @internal

This is the V8.x backport of #896.

Author: oliverklee

CHANGELOG.md

@@ -11,6 +11,7 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ### Changed
 
+- Mark `OutputFormatter` as `@internal` (#896)
 - Mark `Selector::isValid()` as `@internal` (#1037)
 - Mark parsing-related methods of most CSS elements as `@internal` (#908)
 - Mark `OutputFormat::nextLevel()` as `@internal` (#901)

src/OutputFormat.php

@@ -363,12 +363,15 @@ public function beLenient()
 
     /**
      * @return OutputFormatter
+     *
+     * @internal since 8.8.0
      */
     public function getFormatter()
     {
         if ($this->oFormatter === null) {
             $this->oFormatter = new OutputFormatter($this);
         }
+
         return $this->oFormatter;
     }
 

src/OutputFormatter.php

@@ -5,6 +5,9 @@
 use Sabberworm\CSS\Comment\Commentable;
 use Sabberworm\CSS\Parsing\OutputException;
 
+/**
+ * @internal since 8.8.0
+ */
 class OutputFormatter
 {
     /**