import java.io.IOException
import java.net.ProtocolException
import java.net.SocketException
import okhttp3.EventListener
import okhttp3.Headers
import okhttp3.Request
import okhttp3.Response
import okhttp3.ResponseBody
import okhttp3.internal.http.ExchangeCodec
import okhttp3.internal.http.RealResponseBody
import okhttp3.internal.ws.RealWebSocket
import okio.Buffer
import okio.ForwardingSink
import okio.ForwardingSource

import assertk.assertions.isNotNull
import assertk.assertions.matches
import assertk.assertions.message
import okhttp3.Protocol
import okhttp3.Request
import okhttp3.Response
import okhttp3.ResponseBody.Companion.toResponseBody
import okhttp3.brotli.internal.uncompress
import okio.Buffer
import okio.BufferedSource
import okio.ByteString
import okio.ByteString.Companion.decodeHex
import okio.IOException

      Response.Builder()
        .request(Request("https://example.com/".toHttpUrl()))
        .protocol(Protocol.HTTP_1_1)
        .message("OK")
        .code(200)
        .body(
          object : ResponseBody() {
            override fun contentType() = null

            override fun contentLength() = -1L

            override fun source() =
              object : ForwardingSource(Buffer()) {

import java.io.IOException
import kotlin.test.assertFailsWith
import okhttp3.MediaType.Companion.toMediaType
import okhttp3.Protocol
import okhttp3.Request
import okhttp3.Response
import okhttp3.ResponseBody.Companion.toResponseBody
import okhttp3.brotli.internal.uncompress
import okio.ByteString
import okio.ByteString.Companion.EMPTY
import okio.ByteString.Companion.decodeHex
import okio.ByteString.Companion.encodeUtf8

    /** This is only part that's allowed to read from the underlying source. */
    private var currentPart: PartSource? = null

    @Throws(IOException::class)
    constructor(response: ResponseBody) : this(
      source = response.source(),
      boundary =
        response.contentType()?.parameter("boundary")
          ?: throw ProtocolException("expected the Content-Type to have a boundary parameter"),
    )

!!! note "Hinweis"
    Einige Responsecodes (siehe nächster Abschnitt) kennzeichnen, dass die Response keinen Body hat.

    FastAPI versteht das und wird in der OpenAPI-Dokumentation anzeigen, dass es keinen Responsebody gibt.

## Über HTTP-Statuscodes

!!! note "Hinweis"
    Wenn Sie bereits wissen, was HTTP-Statuscodes sind, überspringen Sie dieses Kapitel und fahren Sie mit dem nächsten fort.

   * [RequestBody.writeTo] after that method returns. For duplex requests bodies that condition is
   * lifted. Such writes occur on an application-provided thread and may occur concurrently with
   * reads of the [ResponseBody]. For duplex request bodies, [writeTo] should return
   * quickly, possibly by handing off the provided request body to another thread to perform
   * writing.
   *