feat: LineItems for shipment/order creation (#644)

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# Pull Request Type

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- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
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- [ ] Improvement (fixing a typo, updating readme, renaming a variable
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Author: Justintime50

CHANGELOG.md

@@ -8,6 +8,7 @@
   - `ApiKey.Enable`
   - `ApiKey.Disable`
 - Adds `Tracker.Delete` function
+- Adds `LineItems` to the shipment/order create parameter set
 
 ## v7.4.0 (2025-11-24)
 

EasyPost/Parameters/Shipment/Create.cs

@@ -154,6 +154,29 @@ public class Create : BaseParameters<Models.API.Shipment>, IShipmentParameter
         [NestedRequestParameter(typeof(Luma.CreateAndBuy), Necessity.Optional, "carrier_accounts")]
         public List<string>? CarrierAccountIds { get; set; }
 
+        /// <summary>
+        ///     A list of line items for the new <see cref="Models.API.Shipment"/>.
+        /// </summary>
+        [TopLevelRequestParameter(Necessity.Optional, "shipment", "line_items")]
+        [NestedRequestParameter(typeof(Order.Create), Necessity.Optional, "line_items")]
+        public List<LineItem>? LineItems { get; set; }
+
+        /// <summary>
+        ///     Represents a line item for a shipment.
+        /// </summary>
+        public class LineItem
+        {
+            /// <summary>
+            ///     The total value of the line item.
+            /// </summary>
+            public string? TotalLineValue { get; set; }
+
+            /// <summary>
+            ///     The description of the item.
+            /// </summary>
+            public string? ItemDescription { get; set; }
+        }
+
         #endregion
     }
 }