The username and password parameters to `Credentials.basic()` are now non-null strings. In OkHttp
3.x, null would yield a username or password of "null".

#### HttpUrl.queryParameterValues()

The return type of `HttpUrl.queryParameterValues()` is `List<String?>`. Lists that may contain null
are uncommon and Kotlin callers may have incorrectly assigned the result to `List<String>`.


Code Cleanup
------------

        goodCertificate.certificate,
      )
    server.useHttps(socketFactory)
    server.enqueue(
      MockResponse.Builder()
        .body("abc")
        .addHeader("Content-Type: text/plain")
        .build(),
    )

    // Make a request from client to server. It should succeed certificate checks (unfortunately the
    // rogue CA is trusted) but it should fail certificate pinning.

  }

  @Test
  fun kotlinReifiedTag() {
    val uuidTag = "1234"
    val request =
      Request.Builder()
        .url("https://square.com")
        .tag<String>(uuidTag) // Use the type parameter.
        .build()
    assertThat(request.tag<String>()).isSameAs("1234")
    assertThat(request.tag<Any>()).isNull()

    // Alternate access APIs also work.

      Header("content-encoding", ""),
      Header("content-language", ""),
      Header("content-length", ""),
      Header("content-location", ""),
      Header("content-range", ""),
      Header("content-type", ""),
      Header("cookie", ""),
      Header("date", ""),
      Header("etag", ""),
      Header("expect", ""),
      Header("expires", ""),
      Header("from", ""),
      Header("host", ""),