Please answer these questions before submitting your issue.

What version of gRPC are you using?

1.23

What did you expect to see?

okhttp3 is more than 3 years old now (released in 2016-01-13). Please upgrade grpc-okhttp to use okhttp3.
Indeed a lot of android apps now use okhttp3 to make http requests. But if an android app also uses grpc, it must still embed okhttp 2.5.0 library.

Kind regards,

Laurent