Refactor `AbstractSimpleTransportTestCase` and `MockTransportService` to not use `Version.transportVersion` 
modules/transport-netty4/src/test/java/org/elasticsearch/transport/netty4/SimpleNetty4TransportTests.java
new DiscoveryNode(
                    "C",
                    new TransportAddress(InetAddress.getByName("localhost"), 9876),
                    emptyMap(),
                    emptySet(),
                    Version.CURRENT
                )
            );
            fail("Expected ConnectTransportException");
        } catch (ConnectTransportException e) {
            assertThat(e.getMessage(), containsString("connect_exception"));
            assertThat(e.getMessage(), containsString("[127.0.0.1:9876]"));
        }
    }
    public void testDefaultKeepAliveSettings() throws IOException {
        assumeTrue("setting default keepalive options not supported on this platform", (IOUtils.LINUX || IOUtils.MAC_OS_X));
        try (
            MockTransportService serviceC = buildService("TS_C", Version.CURRENT, Settings.EMPTY);
            MockTransportService serviceD = buildService("TS_D", Version.CURRENT, Settings.EMPTY)
        ) {
            try (Transport.Connection connection = openConnection(serviceC, serviceD.getLocalDiscoNode(), TestProfiles.LIGHT_PROFILE)) {
                assertThat(connection, instanceOf(StubbableTransport.WrappedConnection.class));
                Transport.Connection conn = ((StubbableTransport.WrappedConnection) connection).getConnection();
                assertThat(conn, instanceOf(TcpTransport.NodeChannels.class));
                TcpTransport.NodeChannels nodeChannels = (TcpTransport.NodeChannels) conn;
                for (TcpChannel channel : nodeChannels.getChannels()) {
                    assertFalse(channel.isServerChannel());
                    checkDefaultKeepAliveOptions(channel);
                }
                assertThat(serviceD.getOriginalTransport(), instanceOf(TcpTransport.class));