Changes

In fact, Umlaut does not currently use ServiceResponse caching across requests; it turned out to be tricky to get right without clear gain. And very few (if any?) current services register the same ServiceResponse to a request with multiple ServiceTypeValues. But, the architecture is there to support it if needed in the future.

 This data structure is architecture ends up somewhat confusing, (and ServiceType is probably not a clear name for that three-way join) but there are usually convenience methods defined to avoid the complexity; they should be used. See for example (tbd).