src/main/java/com/authlete/jaxrs/BaseEndpoint.java
protected String[] extractClientCertificateChain(HttpServletRequest request)
    {
        for (ClientCertificateExtractor extractor : clientCertificateExtractors)
        {
            String[] chain = extractor.extractClientCertificateChain(request);
            if (chain != null && chain.length > 0)
            {
                return chain;
            }
        }

        return null;
    }
protected String[] extractClientCertificateChain(HttpServletRequest request)
    {
        for (ClientCertificateExtractor extractor : clientCertificateExtractors)
        {
            String[] chain = extractor.extractClientCertificateChain(request);
            if (chain != null && chain.length > 0)
            {
                return chain;
            }
        }

        return null;
    }
Utility method for extracting a single client certificate from the default
certificate extractors. First checks the request itself for an attached
certificate using {@link javax.servlet.request.X509Certificate}, then
checks the incoming request headers for reverse-proxied certificates
using default headers.

@see ClientCertificateExtractor

@param request
The incoming HTTP request to search for the client's certificate.

@return
The client's mutual TLS certificate.

@since 2.8