Entities: Use 'required' and '= null!' to get rid of warnings

Elwig/Models/Entities/AT_Plz.cs

@@ -9,13 +9,13 @@ namespace Elwig.Models.Entities {
         public int Plz { get; private set; }
 
         [Column("ort")]
-        public string Ort { get; private set; }
+        public string Ort { get; private set; } = null!;
 
         [Column("blnr")]
         public int BlNr { get; private set; }
 
         [Column("type")]
-        public string Type { get; private set; }
+        public string Type { get; private set; } = null!;
 
         [Column("internal")]
         public bool IsInternal { get; private set; }
@@ -27,6 +27,6 @@ namespace Elwig.Models.Entities {
         public bool IsPoBox { get; private set; }
 
         [InverseProperty("AtPlz")]
-        public virtual ISet<AT_PlzDest> Orte { get; private set; }
+        public virtual ISet<AT_PlzDest> Orte { get; private set; } = null!;
     }
 }