The kcfg format is defined by the file kcfg.xsd that is also in this repository. A number of files did not pass validation against kcfg.xsd.
I added a dummy entry to
test_emptyentries.kcfg which might not be the best option.
Validity can be checked with:
xmlstarlet val -e -s ./src/kconfig_compiler/kcfg.xsd autotests/kconfig_compiler/*.kcfg