I don't believe it's fixable at all if you're using someone's third-party library that wasn't designed for GSON (unless something has changed a lot since I last

I don't believe it's fixable at all if you're using someone's third-party library that wasn't designed for GSON (unless something has changed a lot since I last used it). The annotation has to be stuck on the original field, AFAIK. And similar stuff apply to other invariants on the type. I believe these kinds of issues are somewhat fundamental when you decide you're going to start (de)serializing structures that never thought about whether or how they'd like that to happen.