kubernetes/vendor/go.etcd.io/etcd/client/pkg/v3/pathutil/path.go

// CanonicalURLPath returns the canonical url path for p, which follows the rules:
// 1. the path always starts with "/"
// 2. replace multiple slashes with a single slash
// 3. replace each '.' '..' path name element with equivalent one
// 4. keep the trailing slash
// The function is borrowed from stdlib http.cleanPath in server.go.
func CanonicalURLPath(p string) string { … }