Seen in Spring 5.3.18. LinkedHashMap.keySet() tends to return a java.util.LinkedHashMap$LinkedKeySet instance, which is not serializable. This becomes a problem then when you e.g. try to propagate the NoUniqueBeanDefinitionException error across a network boundary (our use case).
Wrapping these in HashSets seem like the simplest way around. The only other call site was passing in an Arrays.asList() object, and asList is explicitly defined to return a serializable list.
(If this change is considered good/safe, it would perhaps be worth back-porting this to the Spring 5 branch as well. It does indeed change the semantics, but it could also arguably be considered a back-port safe bug fix.)
Thanks for a great project! :pray:
Comment From: pivotal-cla
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Comment From: perlun
(Test failure seems unrelated to me. :thinking:)
Comment From: snicoll
Thanks again @perlun and that's a good catch. Rather than doing this at the caller level, I've fixed the exception itself so that it creates a copy of the collection. This is similar to what we do for arrays.