Posted by Alexander Schwartz on Oct 17, 2019; 5:49pm
URL: https://discuss.asciidoctor.org/Extending-asciidoctordiagram-tp7240p7244.html

Every supported diagram type in Asciidoctor Diagram is itself an extension of Asciidoctor and depends on a common DiagramConverter provided by Asciidoctor Diagram.

You should be able to add a new diagram type by following the example of for example PlantUML: https://github.com/asciidoctor/asciidoctor-diagram/blob/master/lib/asciidoctor-diagram/plantuml.rb and https://github.com/asciidoctor/asciidoctor-diagram/tree/master/lib/asciidoctor-diagram/plantuml

As adding new diagram types depend on Asciidoctor Diagram Ruby code, I doubt that you can write add a diagram type by using just Java code although I might be mistaken here.

Regards,
Alexander