void put(Class clazz, String propertyName, Method method)
        {
            ConcurrentHashMap<String,Method> methodsByPropertyName = this.cache.get(clazz);
            if (methodsByPropertyName == null)
            {
                methodsByPropertyName = new ConcurrentHashMap<String, Method>();
                this.cache.put(clazz, methodsByPropertyName);
            }
            methodsByPropertyName.put(propertyName, (method == null? NULL_REPLACEMENT : method));
        }