I am having a problem with copying the AddData widget and importing as a custom widget into ArcGIS Portal 10.5.1
Steps to reproduce:
1. Create a Web Application builder project Web Application Developer.
2. Add the "Add Data" widget to the project.
3. Save the project.
4. Download/Export the WAB Developer project.
5. Publish the project to a web server. (not the same server as the portal server)
6. In ArcGIS Portal, add the widget that was published in step 5 as a custom widget by referencing the manifest file in the Add Item -> Application -> Application Extension.
7. Create another Web Application builder project in ArcGIS portal.
