Refactor `AbstractSimpleTransportTestCase` and `MockTransportService` to not use `Version.transportVersion` 
test/framework/src/main/java/org/elasticsearch/transport/AbstractSimpleTransportTestCase.java
TransportRequestOptions.EMPTY,
                transportResponseHandler
            );
            receivedLatch.await();
            serviceC.close();
            sendResponseLatch.countDown();
            responseLatch.await();
        }
    }
    public void testTransportStats() throws Exception {
        MockTransportService serviceC = buildService("TS_C", version0, Settings.EMPTY);
        CountDownLatch receivedLatch = new CountDownLatch(1);
        CountDownLatch sendResponseLatch = new CountDownLatch(1);
        serviceB.registerRequestHandler("internal:action", ThreadPool.Names.SAME, TestRequest::new, (request, channel, task) -> {
            
            threadPool.generic().execute(new AbstractRunnable() {
                @Override
                public void onFailure(Exception e) {
                    try {
                        channel.sendResponse(e);
                    } catch (IOException e1) {
                        throw new UncheckedIOException(e1);
                    }
                }
                @Override
                protected void doRun() throws Exception {
                    receivedLatch.countDown();
                    sendResponseLatch.await();
                    channel.sendResponse(TransportResponse.Empty.INSTANCE);
                }