I feel like the simple answer is that there's no guaranteed order. An order isn't really an inherent property of a Java Map object.
Even if you get a particular order now, I wouldn't suggest that your write your code expecting that outcome in the future, as it could change in future versions of the platform.
The fact that you're asking this question makes me suspicious you are trying to solve a problem using a non-optimal solution. You should consider posting the original problem that lead you to this question on the forum instead.