@Override
    public void set(final String messageID, final XMLObject message) {
        LOGGER.debug("Storing message {} to session {}", messageID,
            sessionStore.getSessionId(context, true).orElseThrow());
        val messages = getMessages();
        messages.put(messageID, Configuration.serializeSamlObject(message).toString());
        updateSession(messages);
    }
{@inheritDoc}

Stores a request message into the repository. RequestAbstractType must have an ID
set. Any previous message with the same ID will be overwritten.
pac4j-saml/src/main/java/org/pac4j/saml/store/HttpSessionStore.java