@Override
        @JsonIgnore
        public JSONObject toJSONObject() {
            return null;
        }
This is {@link NimbusOAuthJacksonModule}.

@author Misagh Moayyed
@since 6.3.0
support/cas-server-support-pac4j-api/src/main/java/org/apereo/cas/pac4j/serialization/NimbusOAuthJacksonModule.java