Why human nature is inherently good and inherently evil are called Confucian doctrines?

Nature is good is the doctrine of Confucius, who believed that human nature is good. Sex is evil is the doctrine of Mencius, that the evil nature of man is also the nature of man. There is no contradiction, it's just that Confucius was more in favor of having people do good, while Mencius believed that evil was undeniable and innate. For example, 2 plus 2 and 2x2 are both equal to 4.