@Override
    public Map<String, Map<String, Object>> resolveRequestClaims(final WebContext context) throws Exception {
        val supported = jwtBuilder.getCasProperties().getAuthn().getOidc().getDiscovery().isClaimsParameterSupported();

        val claims = FunctionUtils.doIf(supported,
            () -> resolveRequestParameter(context, OAuth20Constants.CLAIMS).map(String::valueOf).orElse(StringUtils.EMPTY),
            () -> StringUtils.EMPTY).get();

        if (StringUtils.isBlank(claims)) {
            return new HashMap<>();
        }
        return MAPPER.readValue(JsonValue.readHjson(claims).toString(), Map.class);
    }
This is {@link DefaultOAuth20RequestParameterResolver}.

@author Misagh Moayyed
@since 6.6.0
support/cas-server-support-oauth-core-api/src/main/java/org/apereo/cas/support/oauth/web/DefaultOAuth20RequestParameterResolver.java