RBF is not disabled by default anymore

But it's not enabled by default either: the developer is forced to
make a decision if he wants to avoid the compile-time warnings.

This way we avoid the potential problems that could have been caused
by simply switching the default to be RFB-enabled, as discussed
originally here: #355

Author: knocte

NBitcoin.Tests/transaction_tests.cs

@@ -335,7 +335,7 @@ public void CanOptInRBF()
 			builder.Send(new Key().ScriptPubKey, Money.Coins(1));
 			builder.SendFees(Money.Coins(0.001m));
 			builder.SetChange(address);
-			builder.OptInRBF = true;
+			builder.RBF = true;
 			var tx = builder.BuildTransaction(false);
 			Assert.True(tx.RBF);
 			foreach(var inp in tx.Inputs)
@@ -349,7 +349,7 @@ public void CanOptInRBF()
 			builder.Send(new Key().ScriptPubKey, Money.Coins(1));
 			builder.SendFees(Money.Coins(0.001m));
 			builder.SetChange(address);
-			builder.OptInRBF = true;
+			builder.RBF = true;
 			builder.SetLockTime(1230944461);
 			tx = builder.BuildTransaction(false);
 			Assert.True(tx.RBF);

NBitcoin/ConsensusFactory.cs

@@ -120,13 +120,32 @@ public virtual TxOut CreateTxOut()
 #pragma warning restore CS0618 // Type or member is obsolete
 		}
 
+		protected virtual TransactionBuilder CreateTransactionBuilderCore(bool RBF)
+		{
+			return new TransactionBuilder(RBF);
+		}
+
+		[Obsolete("Use CreateTransactionBuilder(bool RBF)")]
 		protected virtual TransactionBuilder CreateTransactionBuilderCore()
 		{
 #pragma warning disable CS0618 // Type or member is obsolete
 			return new TransactionBuilder();
 #pragma warning restore CS0618 // Type or member is obsolete
 		}
 
+		/// <summary>
+		/// Creates the transaction builder.
+		/// </summary>
+		/// <returns>The transaction builder.</returns>
+		/// <param name="RBF">If set to <c>true</c>, replace-by-fee will be enabled (recommended, unless you need to keep backwards compatibility with previous transactions built with previous NBitcoin versions, i.e. older than 4.1.2.8).</param>
+		public TransactionBuilder CreateTransactionBuilder(bool RBF)
+		{
+			var builder = CreateTransactionBuilderCore(RBF);
+			builder.SetConsensusFactory(this);
+			return builder;
+		}
+
+		[Obsolete("Use CreateTransactionBuilder(bool RBF)")]
 		public TransactionBuilder CreateTransactionBuilder()
 		{
 #pragma warning disable CS0618 // Type or member is obsolete

NBitcoin/Network.cs

@@ -2513,7 +2513,18 @@ internal NetworkStringParser NetworkStringParser
 			get;
 			set;
 		} = new NetworkStringParser();
+
+		/// <summary>
+		/// Creates the transaction builder for this network.
+		/// </summary>
+		/// <returns>The transaction builder.</returns>
+		/// <param name="RBF">If set to <c>true</c>, replace-by-fee will be enabled (recommended, unless you need to keep backwards compatibility with previous transactions built with previous NBitcoin versions, i.e. older than 4.1.2.8).</param>
+		public TransactionBuilder CreateTransactionBuilder(bool RBF)
+		{
+			return consensus.ConsensusFactory.CreateTransactionBuilder(RBF);
+		}
 
+		[Obsolete("Use CreateTransactionBuilder(bool RBF)")]
 		public TransactionBuilder CreateTransactionBuilder()
 		{
 			return consensus.ConsensusFactory.CreateTransactionBuilder();

NBitcoin/TransactionBuilder.cs

@@ -555,17 +555,22 @@ internal BuilderGroup CurrentGroup
 				return _CurrentGroup;
 			}
 		}
-		[Obsolete("Use Network.CreateTransactionBuilder() or ConsensusFactory.CreateTransactionBuilder() instead")]
-		public TransactionBuilder()
+
+		internal TransactionBuilder(bool RBF)
 		{
 			ShuffleRandom = new Random();
 			CoinSelector = new DefaultCoinSelector(ShuffleRandom);
 			StandardTransactionPolicy = new StandardTransactionPolicy();
 			DustPrevention = true;
-			OptInRBF = false;
+			this.RBF = RBF;
 			InitExtensions();
 		}
 
+		[Obsolete("Use Network.CreateTransactionBuilder() or ConsensusFactory.CreateTransactionBuilder() instead")]
+		public TransactionBuilder() : this(false)
+		{
+		}
+
 		private void InitExtensions()
 		{
 			Extensions.Add(new P2PKHBuilderExtension());
@@ -602,17 +607,17 @@ public bool DustPrevention
 		{
 			get;
 			set;
-		}
-
+		}
+
 		/// <summary>
-		/// If true, it will signal the transaction replaceability in every input. (Default: false)
+		/// If true, it will signal the transaction replaceability in every input.
 		/// </summary>
-		public bool OptInRBF
+		public bool RBF
 		{
 			get;
 			set;
-		}
-
+		}
+
 		/// <summary>
 		/// If true and the transaction has two outputs sending to the same scriptPubKey, those will be merged into a single output. (Default: true)
 		/// </summary>
@@ -1424,7 +1429,7 @@ private IEnumerable<ICoin> BuildTransaction(
 				if(input == null)
 					input = ctx.Transaction.Inputs.Add(coin.Outpoint);
 
-				if(OptInRBF)
+				if(RBF)
 				{
 					input.Sequence = Sequence.OptInRBF;
 					ctx.NonFinalSequenceSet = true;