Unless you rely on a whole tightly coupled environment, like .NET+WCF, or some enterprise Java solutions and the question is based on them - the language in the answer shouldn't matter. If the candidate knows more than one language, they can learn more. Unless you need some specific framework/library knowledge, the rest is just syntax. And that's the least important part of programming.

Exception: first jobs and very inexperienced people. Basically if the answer is given in a specific language because they don't know any other and couldn't produce the answer you want after short time of studying relevant docs, then it may be a real problem.