Upgrade io.grpc + protobuf to OpenJDK compatible versions
The problem is that with the latest OpenJDK builds of JDK 8 (such as u212) GRPC comes across an IllegalAccessException like this: https://github.com/grpc/grpc-java/issues/4933
The only solution is to upgrade GRPC and the Netty it uses to e.g. 1.21.0 along with a more recent Netty.
Edited by Tuukka Lehtonen