Thanks for pointing this out!
This looks very interesting. Integrating this with PlantUML should be possible, and even easiest to do than our own Smetana translation.
(Because it generates a SVG file, so we can reuse the existing code we wrote for regular GraphViz use).
However, it does not parse DOT files. You have to build a graph using objects with some specific API.
We've done something similar with Smetana (except that our API is different)
Honestly the graphviz-java API is really better/prettier than ours, so maybe we are going to copy this API so that both smetana and graphviz-java use a similar API.
We'll see, we are still thinking about all this. Right now, we keep graphviz-java as a possible B-plan.
Anyway, thanks again for pointing this!