some code cleanup

src/Workspaces/Core/Portable/Execution/Serializer.cs

@@ -62,7 +62,7 @@ public Checksum CreateChecksum(object value, CancellationToken cancellationToken
                     case WellKnownSynchronizationKinds.CompilationOptions:
                     case WellKnownSynchronizationKinds.ParseOptions:
                     case WellKnownSynchronizationKinds.ProjectReference:
-                        return Checksum.Create(value, kind, this);
+                        return Checksum.Create(kind, value, this);
 
                     case WellKnownSynchronizationKinds.MetadataReference:
                         return Checksum.Create(kind, _hostSerializationService.CreateChecksum((MetadataReference)value, cancellationToken));

src/Workspaces/Core/Portable/Workspace/Solution/Checksum_Factory.cs

@@ -24,20 +24,19 @@ public static Checksum Create(Stream stream)
             }
         }
 
-        public static Checksum Create(string kind, Checksum checksum)
+        public static Checksum Create(string kind, IObjectWritable @object)
         {
             using (var stream = SerializableBytes.CreateWritableStream())
-            using (var writer = new StreamObjectWriter(stream))
+            using (var objectWriter = new StreamObjectWriter(stream))
             {
-                writer.WriteString(kind);
-                checksum.WriteTo(writer);
+                objectWriter.WriteString(kind);
+                @object.WriteTo(objectWriter);
 
                 return Create(stream);
             }
         }
 
-        public static Checksum Create<TChecksums>(string kind, TChecksums checksums)
-            where TChecksums : IEnumerable<Checksum>
+        public static Checksum Create(string kind, IEnumerable<Checksum> checksums)
         {
             using (var stream = SerializableBytes.CreateWritableStream())
             using (var writer = new StreamObjectWriter(stream))
@@ -69,7 +68,7 @@ public static Checksum Create(string kind, ImmutableArray<byte> bytes)
             }
         }
 
-        public static Checksum Create<T>(T value, string kind, Serializer serializer)
+        public static Checksum Create<T>(string kind, T value, Serializer serializer)
         {
             using (var stream = SerializableBytes.CreateWritableStream())
             using (var objectWriter = new StreamObjectWriter(stream))
@@ -79,17 +78,5 @@ public static Checksum Create<T>(T value, string kind, Serializer serializer)
                 return Create(stream);
             }
         }
-
-        public static Checksum Create(IObjectWritable @object, string kind)
-        {
-            using (var stream = SerializableBytes.CreateWritableStream())
-            using (var objectWriter = new StreamObjectWriter(stream))
-            {
-                objectWriter.WriteString(kind);
-                @object.WriteTo(objectWriter);
-
-                return Create(stream);
-            }
-        }
     }
 }

src/Workspaces/Core/Portable/Workspace/Solution/DocumentInfo.cs

@@ -234,7 +234,7 @@ Checksum IChecksummedObject.Checksum
                 {
                     if (_lazyChecksum == null)
                     {
-                        _lazyChecksum = Checksum.Create(this, nameof(DocumentAttributes));
+                        _lazyChecksum = Checksum.Create(nameof(DocumentAttributes), this);
                     }
 
                     return _lazyChecksum;

src/Workspaces/Core/Portable/Workspace/Solution/ProjectInfo.cs

@@ -474,7 +474,7 @@ Checksum IChecksummedObject.Checksum
                 {
                     if (_lazyChecksum == null)
                     {
-                        _lazyChecksum = Checksum.Create(this, nameof(ProjectAttributes));
+                        _lazyChecksum = Checksum.Create(nameof(ProjectAttributes), this);
                     }
 
                     return _lazyChecksum;

src/Workspaces/Core/Portable/Workspace/Solution/SolutionInfo.cs

@@ -138,7 +138,7 @@ Checksum IChecksummedObject.Checksum
                 {
                     if (_lazyChecksum == null)
                     {
-                        _lazyChecksum = Checksum.Create(this, nameof(SolutionAttributes));
+                        _lazyChecksum = Checksum.Create(nameof(SolutionAttributes), this);
                     }
 
                     return _lazyChecksum;