Also, Hyrums law are about unforeseen breakage because people did not relay only on the documented API specification. This is undesirable, and in fact hard to

Also, Hyrums law are about unforeseen breakage because people did not relay only on the documented API specification. This is undesirable, and in fact hard to avoid completely. But most breaking changes such as in semantic versioning major number changes do intentionally break client code, which is an entirely different thing. There are a few rules one can follow which make it pretty improbable that such foreseeable breakage will happen. And this will constitute more than 99.9% of API breakage - even more if you stipulate that undocumented features must not be relied upon, and client developers follow that rule. Developers relying on undocumented behavior is usually due to a lack of clear documentation, so it is largely avoidable, too.