Issue #3130107: Extend unit test coverage for LanguageNegotiationContentEntity

core/modules/ckeditor5/js/ckeditor5_plugins/drupalMedia/README.md

-# ckeditor5-drupal-media
-
-Drupal media plugin for CKEditor5
-
-Provides required attributes `data-entity-uuid` and `data-entity-type`.
-
-## Usage
-
-This project is for creating minified js for [Drupal CKEditor5](http://drupal.org/project/ckeditor5)
-
-When using this plugin, you must provide the following config in `drupalMedia`:
-
-1. `libraryURL`: The URL at route media_library.ui to open a browse dialog
-2. `previewURL`: The URL at route media.filter.preview to render a media preview
-3. `openDialog`: The function to open a Drupal dialog
-4. `themeError`: The markup to display if the preview fails
-
-Example config:
-
-```
-ClassicEditor
-  .create(editorElement, {
-    drupalMedia: {
-      libraryURL: '/media-library?...',
-      previewURL: '/media/{filter_format}/preview',
-      openDialog: Drupal.ckeditor5.openDialog,
-      themeError: Drupal.theme('mediaEmbedPreviewError'),
-    },
- });
-  .then( ... )
-  .catch( ... );
-```
-
-## Build
-
-Run `npm run dll:build` to create the minified js.
-
-Check the file path in `webpack.config.js` to ensure it points to the dll
-manifest in your copy of `ckeditor5`.