SqlStreamInput/Output use TransportVersion from a read-in Version constant. We need to remove the useage of `transportVersion` field
x-pack/plugin/sql/qa/mixed-node/src/javaRestTest/java/org/elasticsearch/xpack/sql/qa/mixed_node/SqlCompatIT.java
import org.elasticsearch.xpack.sql.qa.rest.BaseRestSqlTestCase;
import org.hamcrest.Matchers;
import org.junit.AfterClass;
import org.junit.Before;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
import static org.elasticsearch.xpack.ql.TestUtils.buildNodeAndVersions;
public class SqlCompatIT extends BaseRestSqlTestCase {
    private static RestClient newNodesClient;
    private static RestClient oldNodesClient;
    private static Version bwcVersion;
    @Before
    public void initBwcClients() throws IOException {
        if (newNodesClient == null) {
            assertNull(oldNodesClient);
            TestNodes nodes = buildNodeAndVersions(client());
            bwcVersion = nodes.getBWCVersion();
            newNodesClient = buildClient(
                restClientSettings(),
                nodes.getNewNodes().stream().map(TestNode::publishAddress).toArray(HttpHost[]::new)
            );
            oldNodesClient = buildClient(
                restClientSettings(),
                nodes.getBWCNodes().stream().map(TestNode::publishAddress).toArray(HttpHost[]::new)
            );
        }