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