@SuppressWarnings("unchecked")
    static <T> Constructor<T> getConstructor(Class<T> clazz,
            Constructor<Object> constructor)
    {
        return (Constructor<T>) sun.reflect.ReflectionFactory
                .getReflectionFactory().newConstructorForSerialization(clazz,
                        constructor);
    }
This class is expected not to load unless {@link RuntimeEnv} made sure that sun.reflect.ReflectionFactory is in the
classpath.

@author David Yu
@created Jul 8, 2011
protostuff-runtime/src/main/java/io/protostuff/runtime/OnDemandSunReflectionFactory.java