private void logUntrustedHostWarning(final ServletRequest request,
                                         final ReceiveDataConfig receiveDataConfig,
                                         final String headerKey) {
        LOGGER.warn("Untrusted host {} ({}) using header {}. The header will be ignored. " +
                    "If the host should be trusted then add the host/IP to the " +
                    "configuration property '{}'",
                request.getRemoteHost(),
                request.getRemoteAddr(),
                headerKey,
                receiveDataConfig.getFullPath(ReceiveDataConfig.PROP_NAME_ALLOWED_CERTIFICATE_PROVIDERS));
    }
Pull out the Subject from the certificate. E.g.
"CN=some.server.co.uk, OU=servers, O=some organisation, C=GB"
stroom-receive/stroom-receive-common/src/main/java/stroom/receive/common/CertificateExtractorImpl.java