String classname = System.getProperty("org.smartfrog.sfcore.languages.csf.consrtaints.SolverClassName");
String classname = System.getProperty("org.smartfrog.sfcore.languages.csf.constraints.SolverClassName");
    public static Solver solver() throws SmartFrogCompileResolutionException {        if (solver == null) {            try {                String classname = System.getProperty("org.smartfrog.sfcore.languages.csf.consrtaints.SolverClassName");                if (classname != null) solverClassname = classname;                solverClass = SFClassLoader.forName(solverClassname);                solver = (Solver) solverClass.newInstance();            } catch (Exception e) {                throw new SmartFrogCompileResolutionException("Unable to construct constraint solver", e);            }        }        return solver;    }