filevault-package-maven-plugin:validate-files reports nodetype related errors validate-package does not

scenario: use content package sample project
https://github.com/stefanseifert/filevault-package-maven-plugin-validation-issues/tree/master/content-packages/conf-content
and execute mvn clean verify (which calls validate-package goal) - all is well, package validation completes successfully.

now execute on the same project with mvn clean test (which calls validate-files goal) - this time the validation fails with:

[ERROR] ValidationViolation: "jackrabbit-nodetypes: Property 'sling:resourceType' [String] is not allowed in node with potential default types [nt:folder]: No applicable property definition found for name and type!", filePath=jcr_root\conf\filevaultsample\settings\.content.xml, nodePath=/conf/filevaultsample/settings, line=4, column=40

why this? it's the same package and the same validators configuration. furthermore, the package content is downloaded from package manager and not created manually, so it should be consistent.

same problem can be reproduced with more validation differences with:
https://github.com/stefanseifert/filevault-package-maven-plugin-validation-issues/tree/master/content-packages/sample-content