#### Credentials.basic()

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
------------

    val querySize: Int = httpUrl.querySize
    val queryParameter: String? = httpUrl.queryParameter("")
    val queryParameterNames: Set<String> = httpUrl.queryParameterNames
    val queryParameterValues: List<String?> = httpUrl.queryParameterValues("")
    val queryParameterName: String = httpUrl.queryParameterName(0)
    val queryParameterValue: String? = httpUrl.queryParameterValue(0)
    val encodedFragment: String? = httpUrl.encodedFragment