Is this a correct implementation of an Immutable class in Java? was migrated from Code Review to Programmers. I think I understand why it was migrated from CodeReview (the author's concern is on making sure the code works, rather than on making working code better). However, I am confused as to why it would be considered conceptual enough to be on Programmers rather than Stackoverflow.
There are traces of an object oriented design question in there, which makes it on topic for Programmers. That, however, doesn't necessarily mean it isn't also on topic for Stack Overflow. The two sites overlap, and it's not uncommon for a question to be suitable for both.
It could even be argued that the question is better suited for Stack Overflow than Programmers, but since it's not completely off topic for us and was answered (correctly) here I see no reason to migrate it.