InputSource source = new InputSource();
source.setLocation( "${expression}" );
source.setModelId( "${expression}" );
Model model = new Model();
model.setLocation( "", new InputLocation( 1, 1, source ) );
SimpleProblemCollector problems = new SimpleProblemCollector();
StringSearchModelInterpolator interpolator = new StringSearchModelInterpolator();
interpolator.interpolateObject( model, model, null, request, problems );