FindGoModDirSubPath find go.mod by traversing dir bottom up, upon finding a go.mod file, it returns the corresponding sub path and root dir.

go list ./pkg.

ListRelativeFiles list all go files, return a list of relative paths.

ParseVendor reads the list of vendored modules from vendor/modules.txt.

see: https://cs.opensource.google/go/go/+/master:src/internal/gover/gover.go.