RxJava1 instrumentation lacks tests

[anuraaga]

There seem to be some indirect tests of Rxjava in other projects but unit tests in its project would make it easier to fix problems related to it's instrumentation.

[trask]

Closed by #2191 and #2672

[anuraaga]

Think this was about rxjava1

[trask]

Closing, it is at least transitively tested via couchbase-2.0 and hystrix-1.4 instrumentation, can revisit later if anyone has renewed interest.