Each HTTP request contains a URL, a method (like `GET` or `POST`), and a list of headers. Requests may also contain a body: a data stream of a specific content type.

## [Responses](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-response/)

The response answers the request with a code (like 200 for success or 404 for not found), headers, and its own optional body.

## Rewriting Requests

    API. Requests made with OkUrlFactory will continue to have a default user
    agent.
 *  New: Guava-like API to create headers:

    ```java
    Headers headers = Headers.of(name1, value1, name2, value2, ...).
    ```

 *  New: Make the content-type header optional for request bodies.
 *  New: `Response.isSuccessful()` is a convenient API to check response codes.

	ctx := t.Context()
	testCases := []struct {
		name            string
		headers         http.Header
		wantObjectAttrs map[string]struct{}
	}{
		{
			name:            "empty header",
			headers:         http.Header{},
			wantObjectAttrs: map[string]struct{}{},
		},
		{
			name: "single header line",
			headers: http.Header{
				xhttp.AmzObjectAttributes: []string{"test1,test2"},
			},

      )
    call1.execute().use { response -> response.body.string() }

    listener.shouldClose = true
    // Large headers are a likely reason the servers would cut off the connection before it completes sending
    // request headers.
    // 431 "Request Header Fields Too Large"
    val largeHeaders =
      Headers
        .Builder()
        .apply {
          repeat(32) {
            add("name-$it", "value-$it-" + "0".repeat(1024))

// getCanonicalHeaders generate a list of request headers with their values
func getCanonicalHeaders(signedHeaders http.Header) string {
	var headers []string
	vals := make(http.Header, len(signedHeaders))
	for k, vv := range signedHeaders {
		k = strings.ToLower(k)
		headers = append(headers, k)
		vals[k] = vv
	}
	sort.Strings(headers)

	var buf bytes.Buffer
	for _, k := range headers {
		buf.WriteString(k)
		buf.WriteByte(':')

each other, corrupt the response cache, and possibly crash your program.

Response caching uses HTTP headers for all configuration. You can add request headers like `Cache-Control: max-stale=3600` and OkHttp's cache will honor them. Your webserver configures how long responses are cached with its own response headers, like `Cache-Control: max-age=9600`. There are cache headers to force a cached response, force a network response, or force the network response to be validated with a conditional...

 */
interface TrailersSource {
  @Throws(IOException::class)
  fun peek(): Headers? = null

  @Throws(IOException::class)
  fun get(): Headers

  companion object {
    @JvmField
    val EMPTY: TrailersSource =
      object : TrailersSource {
        override fun peek() = Headers.EMPTY

        override fun get() = Headers.EMPTY
      }
  }

    }

  fun assertHeader(
    name: String,
    vararg values: String?,
  ) = apply {
    assertThat(response!!.headers(name)).containsExactly(*values)
  }

  fun assertHeaders(headers: Headers) =
    apply {
      assertThat(response!!.headers).isEqualTo(headers)
    }

  fun assertBody(expectedBody: String) =
    apply {
      assertThat(body).isEqualTo(expectedBody)
    }

      .build()
  }

  companion object {
    /** Combines cached headers with a network headers as defined by RFC 7234, 4.3.4. */
    private fun combine(
      cachedHeaders: Headers,
      networkHeaders: Headers,
    ): Headers {
      val result = Headers.Builder()

      for (index in 0 until cachedHeaders.size) {
        val fieldName = cachedHeaders.name(index)

        headers = Headers.headersOf("content-type", "application/json"),
      ),
    )
    server.enqueue(
      MockResponse(
        body =
          """
          |data: hey
          |
          |
          """.trimMargin(),
        headers = Headers.headersOf("content-type", "text/event-stream"),
      ),
    )