private static String[] fetchCaCerts(final Object target) {
        val field = ReflectionUtils.findField(Client.Builder.class, "DEFAULT_CA_CERTS");
        Objects.requireNonNull(field, "Unable to extract default CA certs for Duo Security").trySetAccessible();
        return (String[]) ReflectionUtils.getField(field, target);
    }
Create certificate pinner.

@param host   the host
@param target the target
@return the certificate pinner
support/cas-server-support-duo-core-mfa/src/main/java/org/apereo/cas/adaptors/duo/authn/DuoSecurityClient.java