There is no exportDrawIo task available in docToolchain because such a task is not required. You can continue to use diagrams.net (formerly known as draw.io) to edit your diagrams simply by making a change to your diagram-authoring workflow.

diagrams.net offers free and open source desktop editors for all major operating system platforms. Visit https://www.diagrams.net/integrations to find a desktop editor application compatible with your operating system. When you use the desktop version, just create your diagram with the .png (or even better, .dio.png) extension and diagrams.net will always save your diagram as a PNG with the source as metadata.

They have also launched a free plugin for VS Code and IntelliJ so you can edit your diagrams offline!

Export your diagrams.net/draw.io diagrams as a PNG with the source embedded in the file metadata. This allows you to embed your diagrams into AsciiDoc source as you normally would (using the image:: macro) with the added advantage of storing the diagram source with the image itself.

If you are converting a Confluence page with embedded draw.io diagrams to AsciiDoc, use this export workflow to continue using diagrams.net:

Your diagram can now be managed in source control, added to your documentation source and edited using a diagrams.net desktop version.