I tried to marry Retrofit and Hystrix together but that appears to be quite a cumbersome process. Ideally, I'd like to have something like this

@POST("...")
@HystrixCommand(groupKey="...", commandKey="...")
Observable<SomeObject> get();

However Retrofit uses JDK proxies and annotation info is not preserved so AOP stuff that wires together annotations and actual code does not work. For now, I had to create classes that match methods on interfaces and put @HystrixCommand into class methods instead. That does not look nice as I have to double the code.

Maybe allowing pluggable proxy (cglib, byte-buddy, etc) solution would be helpful in the long term here.