final ExtractData data = new ExtractData(content != null ? content : StringUtil.EMPTY);
            final Enumeration<Header> headers = message.getAllHeaders();
            while (headers.hasMoreElements()) {
                final Header header = headers.nextElement();
                data.putValue(header.getName(), header.getValue());
            }
            putValue(data, "Content-ID", message.getContentID());

    }
  }
  return null
}

internal fun Headers.Builder.commonAdd(
  name: String,
  value: String,
) = apply {
  headersCheckName(name)
  headersCheckValue(value, name)
  commonAddLenient(name, value)
}

internal fun Headers.Builder.commonAddAll(headers: Headers) =
  apply {
    for (i in 0 until headers.size) {
      commonAddLenient(headers.name(i), headers.value(i))
    }
  }

		return code
	}
	return -1
}

func fwdHeadersToS3(h http.Header, w http.ResponseWriter) {
	const trim = "x-amz-fwd-header-"
	for k, v := range h {
		if stringsHasPrefixFold(k, trim) {
			w.Header()[k[len(trim):]] = v
		}
	}
}

func fwdStatusToAPIError(resp *http.Response) *APIError {
	if status := resp.Header.Get(xhttp.AmzFwdStatus); status != "" && StatusCode(status) > -1 {
		apiErr := &APIError{

            }

            data.setContent(EntityUtils.toString(response.getEntity(), Charsets.UTF_8));
            final Header[] headers = response.getAllHeaders();
            for (final Header header : headers) {
                data.putValue(header.getName(), header.getValue());
            }
        } catch (final IOException e) {
            throw new ExtractException(e);
        } finally {

And as the `Response` can be used frequently to set headers and cookies, **FastAPI** also provides it at `fastapi.Response`.

///

## Custom Headers

Keep in mind that custom proprietary headers can be added <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers" class="external-link" target="_blank">using the 'X-' prefix</a>.

def test_incorrect_token():
    response = client.get("/users/me", headers={"Authorization": "Bearer nonexistent"})
    assert response.status_code == 401, response.text
    assert response.json() == {"detail": "Invalid authentication credentials"}
    assert response.headers["WWW-Authenticate"] == "Bearer"


def test_incorrect_token_type():
    response = client.get(
        "/users/me", headers={"Authorization": "Notexistent testtoken"}
    )

      @JvmStatic
      fun create(
        headers: Headers?,
        body: RequestBody,
      ): Part {
        require(headers?.get("Content-Type") == null) { "Unexpected header: Content-Type" }
        require(headers?.get("Content-Length") == null) { "Unexpected header: Content-Length" }
        return Part(headers, body)
      }

      @JvmStatic
      fun createFormData(

    /**
     * Returns the subset of the headers in this's request that impact the content of this's body.
     */
    fun Response.varyHeaders(): Headers {
      // Use the request headers sent over the network, since that's what the response varies on.
      // Otherwise OkHttp-supplied headers like "Accept-Encoding: gzip" may be lost.
      val requestHeaders = networkResponse!!.request.headers
      val responseHeaders = headers

    response = client.get("/users/me", headers={"Authorization": "Bearer nonexistent"})
    assert response.status_code == 401, response.text
    assert response.json() == {"detail": "Invalid authentication credentials"}
    assert response.headers["WWW-Authenticate"] == "Bearer"


@needs_py39
def test_incorrect_token_type(client: TestClient):
    response = client.get(
        "/users/me", headers={"Authorization": "Notexistent testtoken"}

    * But it needs authentication for that specific endpoint.
    * So, to authenticate with our API, it sends a header `Authorization` with a value of `Bearer ` plus the token.
    * If the token contains `foobar`, the content of the `Authorization` header would be: `Bearer foobar`.

## **FastAPI**'s `OAuth2PasswordBearer`