When creating a FileSystemResource with a Path containing .. in the path, then createRelative resolves to a wrong path.

The problem resides on StringUtils::applyRelativePath method: I suggest change the method on FileSystemResource checking first if the location is a Path and then use Path::resolve instead calling StringUtils::applyRelativePath.

println(FileSystemResource(Paths.get("../xxxx/dist/")).createRelative("index.html"))

print ../index.html instead ../xxx/dist/index.html.

Attached image shows the variables inside FileSystemResource::createRelative method.