docs: private void afterExecute(HttpMethod method) throws IOException {
          AuthState hostAuthState = method.getHostAuthState();
          if (hostAuthState.isPreemptive() || hostAuthState.isAuthAttempted()) {
              AuthScheme authScheme = hostAuthState.getAuthScheme();
  
              if (authScheme instanceof SpnegoAuthScheme && settings.getNetworkSpnegoAuthMutual()) {
                  // Perform Mutual Authentication
                  SpnegoAuthScheme spnegoAuthScheme = ((SpnegoAuthScheme) authScheme);
                  Map challenges = AuthChallengeParser.parseChallenges(method.getResponseHeaders(WWW_AUTHENTICATE));
                  String id = spnegoAuthScheme.getSchemeName();
                  String challenge = (String) challenges.get(id.toLowerCase());
                  if (challenge == null) {
                      throw new IOException(id + " authorization challenge expected, but not found");
                  }
                  spnegoAuthScheme.ensureMutualAuth(challenge);
              }
          }
      }