public UnaryCallable<ListRuntimeVersionsRequest, ListRuntimeVersionsResponse>
      listRuntimeVersionsCallable() {
    throw new UnsupportedOperationException("Not implemented: listRuntimeVersionsCallable()");
  }
Base stub class for the Tpu service API.

<p>This class is for advanced usage and reflects the underlying API directly.
java-tpu/google-cloud-tpu/src/main/java/com/google/cloud/tpu/v2/stub/TpuStub.java