Update transitive dependencies

[adriangonz]

Context

On the Java engine, there are a few dependencies which rely on either slightly old versions of sub-dependencies or versions which are lagging a few releases behind. It would be good to keep these up to date. In particular, these are:

• org.checkerframework:checker-qual (through com.google.guava:guava). The version required by guava is v2.8.1, but the latest is v2.11.1.
• com.google.api.grpc:proto-google-common-protos (through io.grpc:grpc-protobuf). The version required by grpc-protobuf is v1.12.0, but the latest is v1.17.0.
• com.squareup.okhttp3:okhttp (through io.jaegertracing:jaeger-client). The version required by jaeger-client is v3.9.0 but the latest is v4.2.2.

Suggested fix

Since we don't have direct control over these libraries, a good short-term solution may be to update them directly on our pom.xml (by excluding the indirect dependencies and adding them as direct ones).

However, it would also be good to submit PRs to the relevant projects so that, in the mid-term, we are able to import new releases of our actual direct dependencies which rely on the newer versions of the indirect ones (after which, the exclusions on our pom.xml wouldn't be needed anymore).