Fixes ConcurrencyError

We run our app servers in Puma under JRuby. Sometimes an app server gets into a bad state, and starts throwing the following error from Apipie:

```
ConcurrencyError (Detected invalid hash contents due to unsynchronized modifications with concurrent users)
```
We have not been able to consistently reproduce this issue, but it appears that several requests executing on the same controller action at the same time cause the options hash to be destructively modified concurrently. From that point forward, all API calls fail.

We believe the attached patch resolves the issue by avoiding destructive modifications.