signature/policy_config.go
func newPRSignedByKeyData(keyType sbKeyType, keyData []byte, signedIdentity PolicyReferenceMatch) (*prSignedBy, error) {
	return newPRSignedBy(keyType, "", keyData, signedIdentity)
}
func newPRSignedByKeyData(keyType sbKeyType, keyData []byte, signedIdentity PolicyReferenceMatch) (*prSignedBy, error) {
	return newPRSignedBy(keyType, "", keyData, signedIdentity)
}
// newPRSignedByKeyData is NewPRSignedByKeyData, except it returns the private type.