Someone depending on it does not mean it becomes the contract. Someone depending on implicit behavior means https://xkcd.com/1172/ https://xkcd.com/1172/ and y

Someone depending on it does not mean it becomes the contract. Someone depending on implicit behavior means https://xkcd.com/1172/ https://xkcd.com/1172/ and you shrug and break them anyway because the contract never required you to uphold the property. It's called contract after all, there's a mutual relationship, not a one-sided one. Otherwise specifications would be meaningless and we would just tell people to read the source.