In applications built with Spring Boot the resources under src/main/resources/ are packed into jar in BOOT-INF/classes/. That's why when in kmodule.xml someone specifies

<kbase name="base" default="true" packages="com.company.*">
...
</kbase>

then for example resource src/main/resources/com/company/rule.drl will not be picked up, because the path in jar(zip) is BOOT-INF/classes/com/company/rule.drl.

From my investigation it seems the logic in org.drools.compiler.kie.builder.impl.KieBuilderImpl#isFileInKieBase does not recognize these files as it compares the packages for equality or if one starts with the other.