Thank you for interest in the GroupDocs.
The GroupDocs.Viewer for Java library is not intended to convert file formats but there is some conversion. When the Viewer is run in the HTML5 mode it converts documents to the composition of the HTML, CSS and SVG objects. So, some part of the document may be converted to the SVG image and then you will be able to save it.
In your case, you can test the GroupDocs.Viewer for Java library with the Spring sample:
Also we have the GroupDocs.Conversion for Java library which is able to convert documents to the image formats and PDF, but there is no SVG conversion available. Dependent on how strong you are interest in using GroupDocs we may investigate this option and add it to our roadmap.