I recently upgraded to OkHttp3, and noticed that you could no longer cancel a Call by tag directly from the Client. This has to be handled by the application now.
Stated in the CHANGELOG here:
Canceling batches of calls is now the application's responsibility. The API to cancel calls by tag has been removed and replaced with a more general mechanism. The dispatcher now exposes all in-flight calls via its runningCalls() and queuedCalls() methods. You can write code that selects calls by tag, host, or whatever, and invokes Call.cancel() on the ones that are no longer necessary.
I'm self-answering this post with my simple utility method to cancel a running or queued Call by tag.