XWIKI-22146: Black square when drag-and-dropping an image in WYSIWYG (#3102)

xwiki-platform-core/xwiki-platform-ckeditor/xwiki-platform-ckeditor-plugins/src/main/webjar/xwiki-filter/plugin.js

@@ -173,7 +173,15 @@
         event.data.dataValue.filter(new CKEDITOR.htmlParser.filter({
           elements: {
             img: function (element) {
-              delete element.attributes['data-widget'];
+              const dataWidgetAttribute = element.attributes['data-widget'];
+              const dataCkeUploadIdAttribute = element.attributes['data-cke-upload-id'];
+              const isUploadImageWidget = dataWidgetAttribute === 'uploadimage';
+              // Cleanup data-widget attributes on images. Except for 'uploadimage' which is only cleaned up when
+              // the image is not currently being uploaded (i.e., has a data-cke-upload-id attribute)
+              if (!isUploadImageWidget || dataCkeUploadIdAttribute === undefined)
+              {
+                delete element.attributes['data-widget'];
+              }
             }
           }
         }));