Just merge the contents of change_this and copy the contents of copy_this into your "older" OXID Shop (< 4.9.6 / 5.2.6) and you are good to go. This codes will provide you with an compatible composer setup like OXID does it in 4.9.6 / 5.2.6.
b3nl/oxid-composer-backport
Inserts the "original" OXID (4.9.6 / 5.2.6) composer setup for older shop versions.
PHPGPL-3.0