public static Class<?> obtainJVMCls(int JPFRef, MJIEnv env, FeatureExpr ctx)
      throws ConversionException {
    if (JPFRef == MJIEnv.NULL) {
      return null;
    }

    ClassInfo ci = env.getReferredClassInfo(ctx, JPFRef);
    JPF2JVMConverter converter = ConverterBase.converterFactory.getJPF2JVMConverter(ci.getName());
    return converter.getJVMCls(JPFRef, env, ctx);
  }
  public static Object obtainJVMObj(int JPFRef, MJIEnv env, FeatureExpr ctx)
      throws ConversionException {
    if (JPFRef == MJIEnv.NULL) {
      return null;
    }

    DynamicElementInfo dei = (DynamicElementInfo) env.getHeap().get(JPFRef);
    ClassInfo ci = dei.getClassInfo();
    JPF2JVMConverter converter = ConverterBase.converterFactory.getJPF2JVMConverter(ci.getName());
    return converter.getJVMObj(JPFRef, env, ctx);
  }