[#3] Move to netstandard 2.0

Signed-off-by: Pavel Gross <p.gross@yadro.com>

src/FrostFS.SDK.ClientV2/Services/ObjectReader.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Threading.Tasks;
+
+using Grpc.Core;
+
+using FrostFS.Object;
+
+namespace FrostFS.SDK.ClientV2;
+
+internal class ObjectReader : IDisposable
+{
+    public AsyncServerStreamingCall<GetResponse> Call { get; set; }
+
+    public async Task<Object.Object> ReadHeader()
+    {
+        if (!await Call.ResponseStream.MoveNext())
+            throw new InvalidOperationException("unexpect end of stream");
+        
+        var response = Call.ResponseStream.Current;
+        Verifier.CheckResponse(response);
+        
+        if (response.Body.ObjectPartCase != GetResponse.Types.Body.ObjectPartOneofCase.Init)
+            throw new InvalidOperationException("unexpect message type");
+        
+        return new Object.Object
+        {
+            ObjectId = response.Body.Init.ObjectId,
+            Header = response.Body.Init.Header,
+        };
+    }
+
+    public async Task<byte[]?> ReadChunk()
+    {
+        if (!await Call.ResponseStream.MoveNext())
+            return null;
+        
+        var response = Call.ResponseStream.Current;
+        Verifier.CheckResponse(response);
+        
+        if (response.Body.ObjectPartCase != GetResponse.Types.Body.ObjectPartOneofCase.Chunk)
+            throw new InvalidOperationException("unexpect message type");
+
+        return response.Body.Chunk.ToByteArray();
+    }
+
+    public void Dispose()
+    {
+        Call.Dispose();
+    }
+}