Added Paths to the XRPL Payment Transaction (#25)

* Added `Paths` to the `XrplPaymentTransaction`.

* Added extension to convert the string representation of XRP drops to a decimal.

Author: DominiqueBlomsma

src/XUMM.NET.SDK/Extensions/CurrencyExtensions.cs

@@ -96,4 +96,15 @@ public static string XrpToDropsString(this decimal value)
 
         return Math.Truncate(value * XrpDrops).ToString();
     }
+
+    /// <summary>
+    /// Convert XRP Drops to the decimal value
+    /// </summary>
+    /// <param name="value">Value in drops</param>
+    /// <returns>Returns the decimal value of the XRP in drops.</returns>
+    public static decimal XrpDropsToDecimal(this string value)
+    {
+        var decimalValue = value.XrplStringNumberToDecimal();
+        return decimalValue / XrpDrops;
+    }
 }

src/XUMM.NET.SDK/Models/Payload/XRPL/XrplPaymentPathSpecification.cs

@@ -0,0 +1,43 @@
+using System;
+using System.Text.Json.Serialization;
+
+namespace XUMM.NET.SDK.Models.Payload.XRPL
+{
+    public class XrplPaymentPathSpecification
+    {
+        /// <summary>
+        /// (Optional) If present, this path step represents rippling through the specified address. MUST NOT be provided if this step specifies the currency or issuer fields.
+        /// </summary>
+        [JsonPropertyName("account")]
+        public string? Account { get; set; }
+
+        /// <summary>
+        /// (Optional) If present, this path step represents changing currencies through an order book. The currency specified indicates the new currency. MUST NOT be provided if this step specifies the account field.
+        /// </summary>
+        [JsonPropertyName("currency")]
+        public string? Currency { get; set; }
+
+        /// <summary>
+        /// (Optional) If present, this path step represents changing currencies and this address defines the issuer of the new currency.
+        /// If omitted in a step with a non-XRP currency, a previous step of the path defines the issuer. If present when currency is omitted,
+        /// indicates a path step that uses an order book between same-named currencies with different issuers. MUST be omitted if the currency is XRP.
+        /// MUST NOT be provided if this step specifies the account field.
+        /// </summary>
+        [JsonPropertyName("issuer")]
+        public string? Issuer { get; set; }
+
+        /// <summary>
+        /// DEPRECATED (Optional) An indicator of which other fields are present.
+        /// </summary>
+        [Obsolete]
+        [JsonPropertyName("type")]
+        public int? Type { get; set; }
+
+        /// <summary>
+        /// DEPRECATED: (Optional) A hexadecimal representation of the type field.
+        /// </summary>
+        [Obsolete]
+        [JsonPropertyName("type_hex")]
+        public string? TypeHex { get; set; }
+    }
+}

src/XUMM.NET.SDK/Models/Payload/XRPL/XrplPaymentTransaction.cs

@@ -47,6 +47,12 @@ public XrplPaymentTransaction()
     [JsonPropertyName("InvoiceID")]
     public string? InvoiceId { get; set; }
 
+    /// <summary>
+    /// (Optional, auto-fillable) Array of payment paths to be used for this transaction. Must be omitted for XRP-to-XRP transactions.
+    /// </summary>
+    [JsonPropertyName("Paths")]
+    public XrplPaymentPathSpecification[][]? Paths { get; set; }
+
     /// <summary>
     /// The amount of currency to deliver. For non-XRP amounts, the nested field names MUST be lower-case. If the
     /// tfPartialPayment flag is set, deliver up to this amount instead.