fix unit test.

src/TensorFlowNET.Core/Functions/ConcreteFunction.cs

@@ -40,7 +40,7 @@ namespace Tensorflow.Functions
         {
             func_graph = graph;
 
-            ToGraph(graph.Inputs, graph.Outputs);
+            ToGraph(graph.Inputs, graph.Outputs.Where(x => x != null).ToArray());
         }
 
         public ConcreteFunction(Func<Tensor, Tensor> func, TF_DataType dtype)

src/TensorFlowNET.Core/Graphs/AutoGraphAttribute.cs

@@ -18,7 +18,7 @@ namespace Tensorflow.Graphs
 
         public override void OnEntry(MethodExecutionArgs args)
         {
-            func_name = $"autograph_{args.Instance.GetHashCode()}.{args.Method.Name}";
+            func_name = $"autograph_{args.Instance.GetType().FullName}.{args.Method.Name}";
 
             if (functions.ContainsKey(func_name))
             {