Not really a question.
I just wanted to point this fact out. Zest/DOT fully implements graphviz dot langage in full java.
With this probably, if working, removing graphviz C library dependency would be doable.
This Eclipse feature provides support for the Graphviz DOT language in Zest: The Eclipse Visualization Toolkit, both as an input and output format. It provides API und UI elements to transform both DOT graphs to Zest visualizations (to be used in Java SWT applications), and Zest visualizations to DOT graphs (to be rendered as image files with Graphviz).