code: private static boolean useBootClasspath(Class clazz) {
          try {
              ParallelWorldClassLoader.toJarUrl(clazz.getResource('/' + clazz.getName().replace('.', '/') + ".class"));
              return true;
          } catch (Exception e) {
              return false;
          }
      }
docs: /*
  To take care of JDK6-JDK6u3, where 2.1 API classes are not there