Http logger always report HTTP 1.1 protocol even for HTTP 2 endpoints.

[lexer]

To reproduce you can this android integration test:

@RunWith(AndroidJUnit4.class)
@LargeTest
public class ApplicationTest extends ApplicationTestCase<Application> {

    public ApplicationTest() {
        super(Application.class);
    }

    @Test
    public void testHttp2() throws IOException {
        HttpLoggingInterceptor loggingInterceptor = new HttpLoggingInterceptor();
        loggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BASIC);

        OkHttpClient okHttpClient = new OkHttpClient.Builder()
                .addInterceptor(loggingInterceptor)
                .build();

        Request request = new Request.Builder()
                .url("https://twitter.com")
                .build();

        Response response = okHttpClient.newCall(request).execute();

        Protocol protocol = response.protocol();

        assertEquals(Protocol.HTTP_2, protocol);

        request = new Request.Builder()
                .url("https://twitter.com/download")
                .build();

        response = okHttpClient.newCall(request).execute();

        protocol = response.protocol();

        assertEquals(Protocol.HTTP_2, protocol);
    }
}

Test logs:

01-14 17:19:21.862 24439-24464/com.github.lexer.http2test I/TestRunner: run started: 1 tests
01-14 17:19:21.867 24439-24464/com.github.lexer.http2test I/TestRunner: started: testHttp2(com.github.lexer.http2test.ApplicationTest)
01-14 17:19:21.870 24439-24439/com.github.lexer.http2test I/MonitoringInstrumentation: Activities that are still in CREATED to STOPPED: 0
01-14 17:19:21.886 24439-24464/com.github.lexer.http2test D/OkHttp: --> GET https://twitter.com/ HTTP/1.1
01-14 17:19:23.525 24439-24464/com.github.lexer.http2test D/OkHttp: <-- 200  https://twitter.com/ (1637ms, -1-byte body)
01-14 17:19:50.231 24439-24464/com.github.lexer.http2test D/OkHttp: --> GET https://twitter.com/download HTTP/1.1
01-14 17:20:17.373 24439-24464/com.github.lexer.http2test D/OkHttp: <-- 200  https://twitter.com/download (27141ms, -1-byte body)
01-14 17:20:17.375 24439-24464/com.github.lexer.http2test I/TestRunner: finished: testHttp2(com.github.lexer.http2test.ApplicationTest)

I think something is probably wrong with how HttpLoggingInterceptor log things.

In all my tests: https://github.com/square/okhttp/blob/master/okhttp-logging-interceptor/src/main/java/okhttp3/logging/HttpLoggingInterceptor.java#L151

connection is always null. So this code block:

    Protocol protocol = connection != null ? connection.protocol() : Protocol.HTTP_1_1;
    String requestStartMessage =
        "--> " + request.method() + ' ' + request.url() + ' ' + protocol(protocol);

Will always return HTTP 1.1