Some people may depend on them, but the difference between API guarantees and implementation details is that developers are far less reluctant to break your legs... I mean your application if you depend on the latter.
For example in java the iteration order of hash maps or the behavior of sorts in presence of non-reflexive comparators changed and people did depend on that. Sun was able to change it because it was not part of the API contract.
For example in java the iteration order of hash maps or the behavior of sorts in presence of non-reflexive comparators changed and people did depend on that. Sun was able to change it because it was not part of the API contract.