Change convert strategies to save xls imported forces

StructureHelperCommon/Models/Forces/FactoredCombinationProperty.cs

@@ -7,11 +7,27 @@ using System.Threading.Tasks;
 
 namespace StructureHelperCommon.Models.Forces
 {
+    /// <inheritdoc/>
     public class FactoredCombinationProperty : IFactoredCombinationProperty
     {
+        /// <inheritdoc/>
+        public Guid Id { get; }
+        /// <inheritdoc/>
         public CalcTerms CalcTerm { get; set; } = CalcTerms.ShortTerm;
+        /// <inheritdoc/>
         public LimitStates LimitState { get; set; } = LimitStates.SLS;
+        /// <inheritdoc/>
         public double LongTermFactor { get; set; } = 1d;
+        /// <inheritdoc/>
         public double ULSFactor { get; set; } = 1.2d;
+        
+        public FactoredCombinationProperty(Guid id)
+        {
+            Id = id;
+        }
+        public FactoredCombinationProperty() : this(Guid.NewGuid())
+        {
+            
+        }
     }
 }