public Serializable generateId(Session session) {
        return UUID.randomUUID().toString();
    }
Ignores the method argument and simply returns
{@code UUID}.{@link java.util.UUID#randomUUID() randomUUID()}.{@code toString()}.

@param session the {@link Session} instance to which the ID will be applied.
@return the String value of the JDK's next {@link UUID#randomUUID() randomUUID()}.
core/src/main/java/org/apache/shiro/session/mgt/eis/JavaUuidSessionIdGenerator.java