Fixes from PR

src/NuGet.Core/NuGet.ProjectModel/LockFile/Utf8JsonStreamLockFileItemConverter.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System;
 using System.Text.Json;
 
 namespace NuGet.ProjectModel
@@ -10,6 +11,13 @@ namespace NuGet.ProjectModel
     /// </summary>
     internal class Utf8JsonStreamLockFileItemConverter<T> : IUtf8JsonStreamReaderConverter<T> where T : LockFileItem
     {
+        private Func<string, T> _lockFileItemCreator;
+
+        public Utf8JsonStreamLockFileItemConverter(Func<string, T> lockFileItemCreator)
+        {
+            _lockFileItemCreator = lockFileItemCreator;
+        }
+
         public T Read(ref Utf8JsonStreamReader reader)
         {
             var genericType = typeof(T);
@@ -21,19 +29,7 @@ public T Read(ref Utf8JsonStreamReader reader)
 
             //We want to read the property name right away
             var lockItemPath = reader.GetString();
-            LockFileItem lockFileItem;
-            if (genericType == typeof(LockFileContentFile))
-            {
-                lockFileItem = new LockFileContentFile(lockItemPath);
-            }
-            else if (genericType == typeof(LockFileRuntimeTarget))
-            {
-                lockFileItem = new LockFileRuntimeTarget(lockItemPath);
-            }
-            else
-            {
-                lockFileItem = new LockFileItem(lockItemPath);
-            }
+            LockFileItem lockFileItem = _lockFileItemCreator(lockItemPath);
 
             reader.Read();
             if (reader.TokenType == JsonTokenType.StartObject)

src/NuGet.Core/NuGet.ProjectModel/LockFile/Utf8JsonStreamLockFileTargetLibraryConverter.cs

@@ -6,7 +6,6 @@
 using System.Text;
 using System.Text.Json;
 using NuGet.Packaging.Core;
-using NuGet.Versioning;
 
 namespace NuGet.ProjectModel
 {
@@ -70,7 +69,7 @@ public LockFileTargetLibrary Read(ref Utf8JsonStreamReader reader)
                 else if (reader.ValueTextEquals(FrameworkAssembliesPropertyName))
                 {
                     reader.Read();
-                    lockFileTargetLibrary.FrameworkAssemblies = reader.ReadStringArrayAsIList(new List<string>());
+                    lockFileTargetLibrary.FrameworkAssemblies = reader.ReadStringArrayAsIList() ?? Array.Empty<string>();
                 }
                 else if (reader.ValueTextEquals(RuntimePropertyName))
                 {
@@ -143,12 +142,11 @@ private IList<PackageDependency> ReadPackageDependencyList(ref Utf8JsonStreamRea
                 return Array.Empty<PackageDependency>();
             }
 
-            var packageDependencies = new List<PackageDependency>();
+            var packageDependencies = new List<PackageDependency>(10);
             while (reader.Read() && reader.TokenType == JsonTokenType.PropertyName)
             {
                 string propertyName = reader.GetString();
                 string versionString = reader.ReadNextTokenAsString();
-
                 packageDependencies.Add(new PackageDependency(
                     propertyName,
                     versionString == null ? null : JsonUtility.ParseVersionRange(versionString)));

src/NuGet.Core/NuGet.ProjectModel/StringExtensions.cs

@@ -2,7 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 #nullable enable
 
-using System;
+using System.Globalization;
 
 namespace NuGet.ProjectModel
 {
@@ -14,11 +14,8 @@ internal static (string firstPart, string? secondPart) SplitInTwo(this string s,
             {
                 return (s, null);
             }
-#if NETCOREAPP2_1_OR_GREATER
-            var index = s.IndexOf(separator, StringComparison.OrdinalIgnoreCase);
-#else
-            var index = s.IndexOf(separator.ToString(), StringComparison.OrdinalIgnoreCase);
-#endif
+            var index = CultureInfo.CurrentCulture.CompareInfo.IndexOf(s, separator, CompareOptions.Ordinal);
+
             if (index == -1)
             {
                 return (s, null);

src/NuGet.Core/NuGet.ProjectModel/Utf8JsonReaderExtensions.cs

@@ -9,9 +9,9 @@ namespace NuGet.ProjectModel
     internal static class Utf8JsonReaderExtensions
     {
         internal static readonly Utf8JsonStreamLockFileConverter LockFileConverter = new Utf8JsonStreamLockFileConverter();
-        internal static readonly Utf8JsonStreamLockFileItemConverter<LockFileItem> LockFileItemConverter = new Utf8JsonStreamLockFileItemConverter<LockFileItem>();
-        internal static readonly Utf8JsonStreamLockFileItemConverter<LockFileContentFile> LockFileContentFileConverter = new Utf8JsonStreamLockFileItemConverter<LockFileContentFile>();
-        internal static readonly Utf8JsonStreamLockFileItemConverter<LockFileRuntimeTarget> LockFileRuntimeTargetConverter = new Utf8JsonStreamLockFileItemConverter<LockFileRuntimeTarget>();
+        internal static readonly Utf8JsonStreamLockFileItemConverter<LockFileItem> LockFileItemConverter = new Utf8JsonStreamLockFileItemConverter<LockFileItem>((string filePath) => new LockFileItem(filePath));
+        internal static readonly Utf8JsonStreamLockFileItemConverter<LockFileContentFile> LockFileContentFileConverter = new Utf8JsonStreamLockFileItemConverter<LockFileContentFile>((string filePath) => new LockFileContentFile(filePath));
+        internal static readonly Utf8JsonStreamLockFileItemConverter<LockFileRuntimeTarget> LockFileRuntimeTargetConverter = new Utf8JsonStreamLockFileItemConverter<LockFileRuntimeTarget>((string filePath) => new LockFileRuntimeTarget(filePath));
         internal static readonly Utf8JsonStreamLockFileTargetLibraryConverter LockFileTargetLibraryConverter = new Utf8JsonStreamLockFileTargetLibraryConverter();
         internal static readonly Utf8JsonStreamLockFileLibraryConverter LockFileLibraryConverter = new Utf8JsonStreamLockFileLibraryConverter();
         internal static readonly Utf8JsonStreamLockFileTargetConverter LockFileTargetConverter = new Utf8JsonStreamLockFileTargetConverter();

src/NuGet.Core/NuGet.ProjectModel/Utf8JsonStreamProjectFileDependencyGroupConverter.cs

@@ -1,7 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-using System.Collections.Generic;
+using System;
 using System.Text.Json;
 
 namespace NuGet.ProjectModel
@@ -20,7 +20,7 @@ public ProjectFileDependencyGroup Read(ref Utf8JsonStreamReader reader)
 
             var frameworkName = reader.GetString();
             reader.Read();
-            var dependencies = reader.ReadStringArrayAsIList(new List<string>());
+            var dependencies = reader.ReadStringArrayAsIList() ?? Array.Empty<string>();
 
             return new ProjectFileDependencyGroup(frameworkName, dependencies);
         }