fix: PrivateKey now implements the Key interface

crypto.go

@@ -332,6 +332,10 @@ func (pk PublicKey) Bytes() []byte {
 	return pk.keyData
 }
 
+func (sk PrivateKey) toProtoKey() *proto.Key {
+	return sk.PublicKey().toProtoKey()
+}
+
 func (pk PublicKey) toProtoKey() *proto.Key {
 	return &proto.Key{Key: &proto.Key_Ed25519{Ed25519: pk.keyData}}
 }

crypto_test.go

@@ -219,3 +219,40 @@ func TestPrivateKey_FromPemWithPassphrase(t *testing.T) {
 
 	assert.Equal(t, actualPrivateKey, privateKey)
 }
+
+func TestSetKeyUsesAnyKey(t *testing.T) {
+	client := newTestClient(t)
+
+	newKey, err := GeneratePrivateKey()
+	assert.NoError(t, err)
+
+	newBalance := NewHbar(1)
+
+	assert.Equal(t, HbarUnits.Hbar.numberOfTinybar(), newBalance.tinybar)
+
+	keys := make([]PrivateKey, 3)
+	pubKeys := make([]PublicKey, 3)
+
+	for i := range keys {
+		newKey, err := GeneratePrivateKey()
+		if err != nil {
+			panic(err)
+		}
+
+		keys[i] = newKey
+		pubKeys[i] = newKey.PublicKey()
+	}
+
+	thresholdKey := KeyListWithThreshold(2).
+		AddAllPublicKeys(pubKeys)
+
+	_, err = NewAccountCreateTransaction().
+		SetKey(newKey.PublicKey()).
+		SetKey(newKey).
+		SetKey(thresholdKey).
+		SetMaxTransactionFee(NewHbar(2)).
+		SetInitialBalance(newBalance).
+		Execute(client)
+	assert.NoError(t, err)
+
+}