Steps to reproduce

1.  Make available the legacy pages app in your admincentral (https://demoauthor.magnolia-cms.com/.magnolia/admincentral#app:configuration;/modules/ui-admincentral/config/appLauncherLayout/hiddenApps:edit)
2.  Allow images in richtext defined within the textImage component in the legacy mtk module  (https://demoauthor.magnolia-cms.com/.magnolia/admincentral#app:resources:edit;/mtk/dialogs/components/textImage.yaml:edit)
3. Create a new Basic page in Legacy pages app and add a textImage component, add an image to the RichText field and save the dialog.
4. Go to Resources app an migrate the textImage dialog (mtk) definition to the new ui (you can use the textImage dialog in mtk2) (remember making images available in the richtext field).
5. Go to new Pages app and open the previously create page and the textImage dialog.

Expected results

Image is displayed in the RichTextField

Actual results

Image is not displayed

Workaround

Development notes

Related to MGNLUI-6527, this ticket is covering the use case in the converter, when the old ui definition is used, but not when the new ui definition is in place (since the converters are not used in this case.

RichTextFieldDefinitionConverter is including a method to do this translation, it might be used as a base for an script.