message: Add comment that registry.PrimitiveFromKeyData does not handle the output prefix.
diff: @@ -94,6 +94,8 @@ func NewKey(kt *tinkpb.KeyTemplate) (proto.Message, error) {
  }
  // PrimitiveFromKeyData creates a new primitive for the key given in the given KeyData.
  +// Note that the returned primitive does not add/remove the output prefix.
  +// It is the caller's responsibility to handle this correctly, based on the key's output_prefix_type.
  func PrimitiveFromKeyData(kd *tinkpb.KeyData) (interface{}, error) {
  if kd == nil {
  return nil, fmt.Errorf("registry.PrimitiveFromKeyData: invalid key data")
  @@ -103,6 +105,8 @@ func PrimitiveFromKeyData(kd *tinkpb.KeyData) (interface{}, error) {
  // Primitive creates a new primitive for the given serialized key using the KeyManager
  // identified by the given typeURL.
  +// Note that the returned primitive does not add/remove the output prefix.
  +// It is the caller's responsibility to handle this correctly, based on the key's output_prefix_type.
  func Primitive(typeURL string, sk []byte) (interface{}, error) {
  if len(sk) == 0 {
  return nil, fmt.Errorf("registry.Primitive: invalid serialized key")
  