Fix erroneous refactorings

Author: tamasvajk

csharp/extractor/Semmle.Extraction.CIL/Entities/Type.cs

@@ -2,7 +2,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Diagnostics.CodeAnalysis;
-using System;
+using System.Linq;
 
 namespace Semmle.Extraction.CIL.Entities
 {
@@ -195,7 +195,7 @@ private bool TryGetPrimitiveTypeCode(out PrimitiveTypeCode code)
 
         protected bool IsPrimitiveType => TryGetPrimitiveTypeCode(out _);
 
-        public sealed override IEnumerable<Type> MethodParameters => throw new NotImplementedException();
+        public sealed override IEnumerable<Type> MethodParameters => Enumerable.Empty<Type>();
 
         public static Type DecodeType(GenericContext gc, TypeSpecificationHandle handle) =>
             gc.Cx.MdReader.GetTypeSpecification(handle).DecodeSignature(gc.Cx.TypeSignatureDecoder, gc);

csharp/extractor/Semmle.Extraction.CIL/Entities/TypeDefinitionType.cs

@@ -6,6 +6,7 @@
 using System.Collections.Generic;
 using System.Reflection;
 using System.IO;
+using System.Reflection.Metadata.Ecma335;
 
 namespace Semmle.Extraction.CIL.Entities
 {
@@ -152,7 +153,7 @@ public override IEnumerable<IExtractionProduct> Contents
         {
             get
             {
-                yield return Tuples.metadata_handle(this, Cx.Assembly, handle.GetHashCode());
+                yield return Tuples.metadata_handle(this, Cx.Assembly, MetadataTokens.GetToken(handle));
 
                 foreach (var c in base.Contents) yield return c;