add and implement IHasEnvelope and IHasReceiver

EnvelopeGenerator.Domain/Entities/EnvelopeReceiver.cs

@@ -1,6 +1,7 @@
 using System.ComponentModel.DataAnnotations;
 using System.ComponentModel.DataAnnotations.Schema;
-using System.Drawing;
+using EnvelopeGenerator.Domain.Interfaces;
+
 #if NETFRAMEWORK
 using System;
 #endif
@@ -13,7 +14,7 @@ namespace EnvelopeGenerator.Domain.Entities
 #endif
 
 [Table("TBSIG_ENVELOPE_RECEIVER", Schema = "dbo")]
-public class EnvelopeReceiver
+public class EnvelopeReceiver : IHasEnvelope, IHasReceiver
 {
     public EnvelopeReceiver()
     {
@@ -70,10 +71,18 @@ public class EnvelopeReceiver
     public bool HasPhoneNumber => !string.IsNullOrWhiteSpace(PhoneNumber);
 
     [ForeignKey("EnvelopeId")]
-    public Envelope Envelope { get; set; }
+    public Envelope
+#if NET
+        ?
+#endif
+            Envelope { get; set; }
 
     [ForeignKey("ReceiverId")]
-    public Receiver Receiver { get; set; }
+    public Receiver
+#if NET
+        ?
+#endif
+            Receiver { get; set; }
 
     #region Model of old serice
     [NotMapped]
@@ -86,8 +95,8 @@ public class EnvelopeReceiver
     public bool HasEmailAndName =>
         !string.IsNullOrWhiteSpace(Receiver.EmailAddress) &&
         !string.IsNullOrWhiteSpace(Name);
-    #endregion
-}
+        #endregion
+    }
 
 #if NETFRAMEWORK
     }