For two specific endpoints in my springboot application I need to use authentication with api key.

At the moment I am trying to implement this in this way according to https://jackynote.medium.com/implementing-multiple-authentication-methods-in-a-spring-boot-3-e57feac77ebd:

SpringSecurityConfig:

@Configuration
@EnableWebSecurity
@RequiredArgsConstructor
@EnableMethodSecurity
@SuppressWarnings("PMD")
public class SecurityConfiguration {

    private final GlobalRestExceptionHandler globalRestExceptionHandler;

    @Bean
    @Order(1)
    public SecurityFilterChain filterChainPrivate(HttpSecurity http) throws Exception {
        http
        .securityMatcher("/specificEndpointToAuthoriseWithApiKey")
        .addFilterBefore(new InternalApiKeyAuthenticationFilter(), ChannelProcessingFilter.class);
        http.cors(AbstractHttpConfigurer::disable);
        http.csrf(AbstractHttpConfigurer::disable);
        http.exceptionHandling(httpSecurityExceptionHandlingConfigurer -> {
            httpSecurityExceptionHandlingConfigurer.accessDeniedHandler(getAccessDeniedHandler());
            httpSecurityExceptionHandlingConfigurer.authenticationEntryPoint(getAuthenticationEntryPoint());
        });
        return http.build();
    }
    @Bean
    @Order(2)
    SecurityFilterChain filterChain(HttpSecurity http,
            Converter<Jwt, ? extends AbstractAuthenticationToken> jwtAuthenticationConverter) throws Exception {

        http.authorizeHttpRequests(accessManagement -> accessManagement
                .requestMatchers(
                        new AntPathRequestMatcher("/api-docs/**"),
                .permitAll()

                .anyRequest().authenticated()
        );`

InternalApiAuthenticationFilter:

import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.net.HttpHeaders;
import jakarta.servlet.Filter;
import jakarta.servlet.FilterChain;
import jakarta.servlet.FilterConfig;
import jakarta.servlet.ServletException;
import jakarta.servlet.ServletRequest;
import jakarta.servlet.ServletResponse;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import org.springframework.http.MediaType;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.web.authentication.WebAuthenticationDetailsSource;
import java.io.IOException;
import java.util.Collections;
import java.util.Map;

public class InternalApiKeyAuthenticationFilter implements Filter {
    private final String internalApiKey = "123456";


    @Override
    public void init(FilterConfig filterConfig) {}

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        HttpServletResponse httpServletResponse = (HttpServletResponse) response;

        String apiKey = httpServletRequest.getHeader("x-api-key");

        if (apiKey == null) {
            unauthorized(httpServletResponse);
            return;
        }

        if (!internalApiKey.equals(apiKey)) {
            unauthorized(httpServletResponse);
            return;
        }

        UsernamePasswordAuthenticationToken authentication = new UsernamePasswordAuthenticationToken(
                "apiKeyUser", null, Collections.singletonList(new SimpleGrantedAuthority("ebf-adapter")));
        authentication.setDetails(new WebAuthenticationDetailsSource().buildDetails(httpServletRequest));
        SecurityContextHolder.getContext().setAuthentication(authentication);
        chain.doFilter(request, response);
    }

    @Override
    public void destroy() {

    }

    private void unauthorized(HttpServletResponse httpServletResponse) throws IOException {
        httpServletResponse.setHeader(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE);
        httpServletResponse.setStatus(401);
        Map<String, Object> response = Map.of("message", "SC_UNAUTHORIZED");
        String responseBody = new ObjectMapper().writeValueAsString(response);
        httpServletResponse.getWriter().write(responseBody);

    }
}`
`
However the endpoint /specificEndpointToAuthoriseWithApiKey deliveres me the following error:
"An Authentication object was not found in the SecurityContext"
I am happy to hear, what am I missing here?