assertThat(headers.name(1)).isEqualTo("c")
    assertFailsWith<IndexOutOfBoundsException> {
      headers.name(2)
    }
  }

  @Test fun valueIndexesAreStrict() {
    val headers = headersOf("a", "b", "c", "d")
    assertFailsWith<IndexOutOfBoundsException> {
      headers.value(-1)
    }
    assertThat(headers.value(0)).isEqualTo("b")
    assertThat(headers.value(1)).isEqualTo("d")

///

## Duplicate headers

It is possible to receive duplicate headers. That means, the same header with multiple values.

You can define those cases using a list in the type declaration.

You will receive all the values from the duplicate header as a Python `list`.

```

////

**FastAPI** will **extract** the data for **each field** from the **headers** in the request and give you the Pydantic model you defined.

## Check the Docs

You can see the required headers in the docs UI at `/docs`:

<div class="screenshot">
<img src="/img/tutorial/header-param-models/image01.png">
</div>

## Forbid Extra Headers

    val headers = headersOf("User-Agent", "RequestTest")
    val request =
      Request(
        url = url,
        headers = headers,
      )
    assertThat(request.url).isEqualTo(url)
    assertThat(request.headers).isEqualTo(headers)
    assertThat(request.method).isEqualTo("GET")
    assertThat(request.body).isNull()
    assertThat(request.tags).isEmpty()
  }

  @Test
  fun constructorNoMethod() {

import java.net.InetAddress
import java.net.Socket
import okhttp3.Headers
import okhttp3.Headers.Companion.headersOf
import okhttp3.internal.EMPTY_HEADERS
import okio.Buffer
import org.junit.jupiter.api.Test
import org.junit.jupiter.api.Timeout

@Timeout(30)
class RecordedRequestTest {
  private val headers: Headers = EMPTY_HEADERS

  @Test fun testIPv4() {
    val socket =
      FakeSocket(

    assertThat(headers.value(0)).isEqualTo("HTTP/1.1")
  }

  @Test fun http2HeadersListDropsForbiddenHeadersHttp2() {
    val request =
      Request.Builder()
        .url("http://square.com/")
        .header("Connection", "upgrade")
        .header("Upgrade", "websocket")
        .header("Host", "square.com")
        .header("TE", "gzip")
        .build()
    val expected =
      headerEntries(

      name: String,
      value: String,
    ) = commonAddHeader(name, value)

    /** Removes all headers named [name] on this builder. */
    open fun removeHeader(name: String) = commonRemoveHeader(name)

    /** Removes all headers on this builder and adds [headers]. */
    open fun headers(headers: Headers) = commonHeaders(headers)

    open fun body(body: ResponseBody) = commonBody(body)

  }

  @Test
  fun headers() {
    var headers: Headers = headersOf("", "")
    headers = mapOf("" to "").toHeaders()
    val get: String? = headers[""]
    val date: Date? = headers.getDate("")
    val instant: Instant? = headers.getInstant("")
    val size: Int = headers.size
    val name: String = headers.name(0)
    val value: String = headers.value(0)
    val names: Set<String> = headers.names()

    assertThat(connect.headers["Proxy-Connection"]).isEqualTo("Keep-Alive")
    assertThat(connect.headers["Host"]).isEqualTo("android.com:443")
    val get = server.takeRequest()
    assertThat(get.headers["Private"]).isEqualTo("Secret")
    assertThat(get.headers["User-Agent"]).isEqualTo("App 1.0")
    assertThat(hostnameVerifier.calls).containsExactly("verify android.com")
  }

  /**

      Headers.Builder()
        .addUnsafeNonAscii("héader1", "value1")
        .build()
    }.also { expected ->
      assertThat(expected.message).isEqualTo("Unexpected char 0xe9 at 1 in header name: héader1")
    }
  }

  @Test fun addUnsafeNonAsciiAcceptsUnicodeValue() {
    val headers =
      Headers.Builder()
        .addUnsafeNonAscii("header1", "valué1")
        .build()