diff --git a/FoodsharingSiegen.Contracts/Entity/Interaction.cs b/FoodsharingSiegen.Contracts/Entity/Interaction.cs
index 02fc2e8..a5a6965 100644
--- a/FoodsharingSiegen.Contracts/Entity/Interaction.cs
+++ b/FoodsharingSiegen.Contracts/Entity/Interaction.cs
@@ -59,7 +59,7 @@ namespace FoodsharingSiegen.Contracts.Entity
         /// <summary>
         ///     Gets or sets the value of the prospect (ab)
         /// </summary>
-        public Prospect Prospect { get; set; }
+        public Prospect Prospect { get; set; } = null!;
 
         /// <summary>
         ///     Gets or sets the value of the prospect id (ab)
@@ -74,7 +74,7 @@ namespace FoodsharingSiegen.Contracts.Entity
         /// <summary>
         ///     Gets or sets the value of the user (ab)
         /// </summary>
-        public User User { get; set; }
+        public User User { get; set; } = null!;
 
         /// <summary>
         ///     Gets or sets the value of the user id (ab)
diff --git a/FoodsharingSiegen.Contracts/Entity/Prospect.cs b/FoodsharingSiegen.Contracts/Entity/Prospect.cs
index d5c7381..a77e593 100644
--- a/FoodsharingSiegen.Contracts/Entity/Prospect.cs
+++ b/FoodsharingSiegen.Contracts/Entity/Prospect.cs
@@ -36,7 +36,7 @@ namespace FoodsharingSiegen.Contracts.Entity
         /// <summary>
         ///     Gets or sets the value of the interactions (ab)
         /// </summary>
-        public IList<Interaction> Interactions { get; set; }
+        public IList<Interaction> Interactions { get; set; } = new List<Interaction>();
 
         /// <summary>
         ///     Gets or sets the value of the memo (ab)
@@ -51,7 +51,7 @@ namespace FoodsharingSiegen.Contracts.Entity
         /// <summary>
         ///     Gets or sets the value of the name (ab)
         /// </summary>
-        public string Name { get; set; }
+        public string Name { get; set; } = string.Empty;
 
         /// <summary>
         ///     Gets or sets the state of the record within the system.
diff --git a/FoodsharingSiegen.Contracts/Entity/User.cs b/FoodsharingSiegen.Contracts/Entity/User.cs
index 8ea2ec4..7fce999 100644
--- a/FoodsharingSiegen.Contracts/Entity/User.cs
+++ b/FoodsharingSiegen.Contracts/Entity/User.cs
@@ -20,7 +20,7 @@ namespace FoodsharingSiegen.Contracts.Entity
         /// <summary>
         ///     Gets or sets the value of the encrypted password (ab)
         /// </summary>
-        public string EncryptedPassword { get; set; }
+        public string EncryptedPassword { get; set; } = string.Empty;
 
         /// <summary>
         ///     Gets or sets the value of the force logout (ab)
@@ -30,7 +30,7 @@ namespace FoodsharingSiegen.Contracts.Entity
         /// <summary>
         ///     Gets or sets the value of the groups (ab)
         /// </summary>
-        public string Groups { get; set; }
+        public string Groups { get; set; } = string.Empty;
 
         /// <summary>
         ///     Gets or sets the value of the groups list (ab)
@@ -57,12 +57,12 @@ namespace FoodsharingSiegen.Contracts.Entity
         /// <summary>
         ///     Gets or sets the value of the interactions (ab)
         /// </summary>
-        public IList<Interaction> Interactions { get; set; }
+        public IList<Interaction> Interactions { get; set; } = new List<Interaction>();
 
         /// <summary>
         ///     Gets or sets the value of the mail (ab)
         /// </summary>
-        public string Mail { get; set; }
+        public string Mail { get; set; } = string.Empty;
 
         /// <summary>
         ///     Gets or sets the value of the memo (ab)
@@ -72,7 +72,7 @@ namespace FoodsharingSiegen.Contracts.Entity
         /// <summary>
         ///     Gets or sets the value of the name (ab)
         /// </summary>
-        public string Name { get; set; }
+        public string Name { get; set; } = string.Empty;
 
         /// <summary>
         ///     Gets or sets the value of the network (ab)