String assertedRDFXML = parameters.getParameteValues("assert")[0].toString();
String revokedRDFXML = parameters.getParameteValues("revoke")[0].toString();
Model assertedModel = ModelFactory.createDefaultModel();
assertedModel
.read(new StringReader(assertedRDFXML), source.getURIRef());
FCAGraph assertedGraph = new FCAGraphImpl(assertedModel);
Model revokedModel = ModelFactory.createDefaultModel();
revokedModel.read(new StringReader(revokedRDFXML), source.getURIRef());
FCAGraph revokedGraph = new FCAGraphImpl(revokedModel);
store.changeGraph(source, revokedGraph, assertedGraph);
}