I know that to upgrade to AEM 6.4 or 6.5 you need to do a lot of restructuring to get things out of /etc. Does AEM 6.3 support those restructuring changes? As in, if, on my custom code, I start making the restructuring changes needed for 6.4/6.5, moving things around and changing the references in code, but still run 6.3, will things keep working or will things start breaking?