This turns out to be somewhat involved since our ASM visitors currently only store annotated methods. With the ASM visitor model, you have to know upfront what you intend to retrieve, so we might be better off providing a dedicated lookup method here - outside of MetadataReader. I'll revisit this for 5.0.2 / 4.3.13.
Folding this into the MetadataReader model is indeed not an option since it conflicts with other purposes, in particular classpath scanning, and I don't want to make compromises there - neither at the API level nor in terms of runtime metadata storage.
We could offer a separate utility with custom use of ASM along the lines of LocalVariableTableParameterNameDiscoverer. Since this requires some internal caching for an efficient solution and since we don't have a use case for it in the core framework, I'd rather put a tailored utility for your purposes into Spring Data Commons instead. We may revisit this once further use cases appear.