JFreeChartWrapper empty behind proxy

Hi together,

when loading a svg graph through a zuul proxy it is not displayed in the UI. You can see it in the image I attached. When calling the svg directly and also when open it behind the proxy within the UI it shows up.

Here is the code I use:

JFreeChart chart = createchart(dataset);
        JFreeChartWrapper jFreeChartWrapper = new JFreeChartWrapper(chart) {
            private static final long serialVersionUID = -7115428425068565513L;

            @Override
            public void attach() {
                super.attach();
                setResource("src", getSource());
            }
        };

Do you have any suggestions about where to look/debug and about what could be the reason?

Thanks in advance
Karsten