string.Empty --> null

Author: Forgind

src/Cli/dotnet/commands/dotnet-workload/WorkloadUtilities.cs

@@ -28,8 +28,8 @@ internal static int VersionCompare(string first, string second)
                 return comparison;
             }
 
-            var modifiedFirst = new ReleaseVersion(1, 1, 1, firstDash == first.Length ? string.Empty : first.Substring(firstDash));
-            var modifiedSecond = new ReleaseVersion(1, 1, 1, secondDash == second.Length ? string.Empty : second.Substring(secondDash));
+            var modifiedFirst = new ReleaseVersion(1, 1, 1, firstDash == first.Length ? null : first.Substring(firstDash));
+            var modifiedSecond = new ReleaseVersion(1, 1, 1, secondDash == second.Length ? null : second.Substring(secondDash));
 
             return modifiedFirst.CompareTo(modifiedSecond);
         }

src/Resolvers/Microsoft.NET.Sdk.WorkloadManifestReader/SdkDirectoryWorkloadManifestProvider.cs

@@ -230,8 +230,8 @@ private static int VersionCompare(string first, string second)
                 return comparison;
             }
 
-            var modifiedFirst = new ReleaseVersion(1, 1, 1, firstDash == first.Length ? string.Empty : first.Substring(firstDash));
-            var modifiedSecond = new ReleaseVersion(1, 1, 1, secondDash == second.Length ? string.Empty : second.Substring(secondDash));
+            var modifiedFirst = new ReleaseVersion(1, 1, 1, firstDash == first.Length ? null : first.Substring(firstDash));
+            var modifiedSecond = new ReleaseVersion(1, 1, 1, secondDash == second.Length ? null : second.Substring(secondDash));
 
             return modifiedFirst.CompareTo(modifiedSecond);
         }