requestBody = byteArrayOf(0, 1).toRequestBody(null, 0, 2)
    requestBody = byteArrayOf(0, 1).toRequestBody("".toMediaTypeOrNull(), 0, 2)
    requestBody = File("").asRequestBody(null)
    requestBody = File("").asRequestBody("".toMediaTypeOrNull())
  }

  @Test
  fun response() {
    val response: Response = Response.Builder().build()
    val request: Request = response.request

import java.util.UUID
import kotlin.test.assertFailsWith
import okhttp3.Headers.Companion.headersOf
import okhttp3.HttpUrl.Companion.toHttpUrl
import okhttp3.MediaType.Companion.toMediaType
import okhttp3.RequestBody.Companion.asRequestBody
import okhttp3.RequestBody.Companion.toRequestBody
import okio.Buffer
import okio.ByteString.Companion.encodeUtf8
import okio.GzipSource
import okio.buffer
import okio.use
import org.junit.jupiter.api.Test

| RequestBody.create(ByteArray)       | ByteArray.toRequestBody()       |
| RequestBody.create(ByteString)      | ByteString.toRequestBody()      |
| RequestBody.create(File)            | File.asRequestBody()            |
| RequestBody.create(String)          | String.toRequestBody()          |
| ResponseBody.create(BufferedSource) | BufferedSource.asResponseBody() |

      fun run() {
        val file = File("README.md")

        val request = Request.Builder()
            .url("https://api.github.com/markdown/raw")
            .post(file.asRequestBody(MEDIA_TYPE_MARKDOWN))
            .build()

        client.newCall(request).execute().use { response ->
          if (!response.isSuccessful) throw IOException("Unexpected code $response")

    import this and we want to ease upgrades for their users.


## Version 4.0.0-RC2

_2019-06-21_

 *  New: Require Kotlin 1.3.40.
 *  New: Change the Kotlin API from `File.toRequestBody()` to `File.asRequestBody()` and
    `BufferedSource.toResponseBody()` to `BufferedSource.asResponseBody()`. If the returned value
    is a view of what created it, we use _as_.
 *  Fix: Permit response codes of zero for compatibility with OkHttp 3.x.

    as the API to read response trailers is unchanged. Testers may use this new stable API to
    supply trailers for a `Response`.

 *  New: `Path.asRequestBody()` is now a non-experimental API.

 *  New: `FileDescriptor.toRequestBody()` is now a non-experimental API.

 *  New: Stop using experimental coroutines APIs in our `okhttp-coroutines` artifact.