docker/daemon/daemon_transport.go
func (ref daemonReference) StringWithinTransport() string {
	switch {
	case ref.id != "":
		return ref.id.String()
	case ref.ref != nil:
		return reference.FamiliarString(ref.ref)
	default: // Coverage: Should never happen, NewReference above should refuse such values.
		panic("Internal inconsistency: daemonReference has empty id and nil ref")
	}
}
func (ref daemonReference) StringWithinTransport() string {
	switch {
	case ref.id != "":
		return ref.id.String()
	case ref.ref != nil:
		return reference.FamiliarString(ref.ref)
	default: // Coverage: Should never happen, NewReference above should refuse such values.
		panic("Internal inconsistency: daemonReference has empty id and nil ref")
	}
}
// StringWithinTransport returns a string representation of the reference, which MUST be such that
// reference.Transport().ParseReference(reference.StringWithinTransport()) returns an equivalent reference.
// NOTE: The returned string is not promised to be equal to the original input to ParseReference;
// e.g. default attribute values omitted by the user may be filled in in the return value, or vice versa.
// WARNING: Do not use the return value in the UI to describe an image, it does not contain the Transport().Name() prefix;
// instead, see transports.ImageName().