* @param token the authorization data token
     * @param keys the Kerberos keys for decryption
     * @return a list of parsed authorization data
     * @throws PACDecodingException if the data cannot be decoded
     */
    public static List<KerberosAuthData> parse(int authType, byte[] token, Map<Integer, KerberosKey> keys) throws PACDecodingException {

        )

    async def __call__(
        self, request: Request
    ) -> Optional[HTTPAuthorizationCredentials]:
        authorization = request.headers.get("Authorization")
        scheme, credentials = get_authorization_scheme_param(authorization)
        if not (authorization and scheme and credentials):
            if self.auto_error:
                raise self.make_not_authenticated_error()
            else:

    /**
     * Test case for when the 'Authorization' header is missing.
     * Expects the server to respond with a 'WWW-Authenticate: NTLM' header and a 401 status.
     * @throws IOException
     */
    @Test
    public void testAuthenticate_NoAuthorizationHeader() throws IOException {
        // Setup: No "Authorization" header
        when(mockRequest.getHeader("Authorization")).thenReturn(null);

        // Execute

		expectedErr error
	}{
		// Set valid authorization header.
		{
			req: &http.Request{
				Header: http.Header{
					"Authorization": []string{token},
				},
			},
			expectedErr: nil,
		},
		// No authorization header.
		{
			req: &http.Request{
				Header: http.Header{},
			},
			expectedErr: errNoAuthToken,
		},
		// Invalid authorization token.
		{
			req: &http.Request{

        // Initialize filter first
        initializeFilter();

        // Test request without Authorization header should challenge client
        when(request.getHeader("Authorization")).thenReturn(null);
        when(httpSession.getAttribute("NtlmHttpAuth")).thenReturn(null);

        filter.doFilter(request, response, filterChain);

    * This automatic discovery is what is defined in the OpenID Connect specification.


/// tip

Integrating other authentication/authorization providers like Google, Facebook, X (Twitter), GitHub, etc. is also possible and relatively easy.

The most complex problem is building an authentication/authorization provider like those, but **FastAPI** gives you the tools to do it easily, while doing the heavy lifting for you.

///

def test_token(mod: ModuleType):
    client = TestClient(mod.app)
    access_token = get_access_token(scope="me", client=client)
    response = client.get(
        "/users/me", headers={"Authorization": f"Bearer {access_token}"}
    )
    assert response.status_code == 200, response.text
    assert response.json() == {
        "username": "johndoe",
        "full_name": "John Doe",

        )

    async def __call__(self, request: Request) -> Optional[str]:
        authorization = request.headers.get("Authorization")
        if not authorization:
            if self.auto_error:
                raise self.make_not_authenticated_error()
            else:
                return None

        )

    async def __call__(self, request: Request) -> Optional[str]:
        authorization = request.headers.get("Authorization")
        if not authorization:
            if self.auto_error:
                raise self.make_not_authenticated_error()
            else:
                return None
        return authorization


class OAuth2PasswordBearer(OAuth2):
    """

 * and the implementation should respond with a new request that sets the "Authorization" header.
 *
 * ```java
 * if (response.request().header("Authorization") != null) {
 *   return null; // Give up, we've already failed to authenticate.
 * }
 *
 * String credential = Credentials.basic(...)
 * return response.request().newBuilder()
 *     .header("Authorization", credential)
 *     .build();
 * ```
 *