Port stratis fixes for OP_RETURN in transaction building (#224)

* Add opreturn amounts from stratis fix

* OP_RETURN fixes from stratis 3.0.8.0 release branch

Author: xandronus

src/Features/Blockcore.Features.Wallet/Api/Models/RequestModels.cs

@@ -321,8 +321,6 @@ public TxFeeEstimateRequest()
         /// recipient will receive in STRAT (or a sidechain coin). If the transaction was realized,
         /// both the values would be used to create the UTXOs for the transaction recipients.
         /// </summary> 
-        [Required(ErrorMessage = "A list of recipients is required.")]
-        [MinLength(1)]
         public List<RecipientModel> Recipients { get; set; }
 
         /// <summary>

src/Features/Blockcore.Features.Wallet/WalletTransactionHandler.cs

@@ -304,7 +304,7 @@ protected void AddCoins(TransactionBuildContext context)
 
             // Get total spendable balance in the account.
             long balance = context.UnspentOutputs.Sum(t => t.Transaction.Amount);
-            long totalToSend = context.Recipients.Sum(s => s.Amount);
+            long totalToSend = context.Recipients.Sum(s => s.Amount) + (context.OpReturnAmount ?? Money.Zero);
             if (balance < totalToSend)
                 throw new WalletException("Not enough funds.");
 

src/Tests/Blockcore.Features.Wallet.Tests/WalletControllerTest.cs

@@ -1634,7 +1634,7 @@ public void BuildTransactionWithChangeAddressReturnsWalletBuildTransactionModel(
             IActionResult result = controller.BuildTransaction(new BuildTransactionRequest
             {
                 AccountName = "Account 0",
-                Recipients = new List<RecipientModel>(),
+                Recipients = new List<RecipientModel>() { new RecipientModel() { Amount = "1.0", DestinationAddress = new Key().PubKey.Hash.GetAddress(this.Network).ToString() } },
                 WalletName = walletName,
                 ChangeAddress = usedReceiveAddress.Address
             });
@@ -1676,7 +1676,7 @@ public void BuildTransactionWithChangeAddressNotInWalletReturnsBadRequest()
             IActionResult result = controller.BuildTransaction(new BuildTransactionRequest
             {
                 AccountName = "Account 0",
-                Recipients = new List<RecipientModel>(),
+                Recipients = new List<RecipientModel>() { new RecipientModel() { Amount = "1.0", DestinationAddress = new Key().PubKey.Hash.GetAddress(this.Network).ToString() } },
                 WalletName = walletName,
                 ChangeAddress = addressNotInWallet.Address
             });
@@ -1713,7 +1713,7 @@ public void BuildTransactionWithChangeAddressAccountNotInWalletReturnsBadRequest
             IActionResult result = controller.BuildTransaction(new BuildTransactionRequest
             {
                 AccountName = "Account 0",
-                Recipients = new List<RecipientModel>(),
+                Recipients = new List<RecipientModel>() { new RecipientModel() { Amount = "1.0", DestinationAddress = new Key().PubKey.Hash.GetAddress(this.Network).ToString() } },
                 WalletName = walletName,
                 ChangeAddress = addressNotInWallet.Address
             });