Export to SVG is not working

[MohamedLEGH]

This is what I get with the graph.display() function (and with System.setProperty("org.graphstream.ui", "swing")):

And this is what I get with

FileSinkSVG fsi = new FileSinkSVG();
fsi.writeAll(graph, "test.svg");

I also tested with FileSinkUnstyledSVG but the svg output is not even readable.