kubernetes/vendor/sigs.k8s.io/json/internal/golang/encoding/json/fold.go

// foldName returns a folded string such that foldName(x) == foldName(y)
// is identical to bytes.EqualFold(x, y).
func foldName(in []byte) []byte { … }

func appendFoldedName(out, in []byte) []byte { … }

// foldRune is returns the smallest rune for all runes in the same fold set.
func foldRune(r rune) rune { … }