Issue 458 hatch clone fix

src/ACadSharp.Tests/IO/LocalSampleTests.cs

@@ -34,6 +34,14 @@ public void ReadUserDwg(FileModel test)
 				return;
 
 			CadDocument doc = DwgReader.Read(test.Path, this._dwgConfiguration, this.onNotification);
+
+			CadDocument newDoc = new CadDocument();
+
+			foreach (var entity in doc.Entities)
+			{
+				doc.Entities.Remove(entity);
+				newDoc.Entities.Add(entity);
+			}
 		}
 
 		[Theory]

src/ACadSharp/Entities/Hatch.cs

@@ -151,7 +151,7 @@ public override CadObject Clone()
 			clone.GradientColor = this.GradientColor?.Clone();
 			clone.Pattern = this.Pattern?.Clone();
 
-			clone.Paths.Clear();
+			clone.Paths = new List<BoundaryPath>();
 			foreach (BoundaryPath item in this.Paths)
 			{
 				clone.Paths.Add(item.Clone());

src/ACadSharp/Entities/HatchPattern.cs

@@ -57,7 +57,7 @@ public HatchPattern Clone()
 		{
 			HatchPattern clone = (HatchPattern)this.MemberwiseClone();
 
-			clone.Lines.Clear();
+			clone.Lines = new List<Line>();
 			foreach (var item in this.Lines)
 			{
 				clone.Lines.Add(item.Clone());