diff --git a/src/ChangeLog.Test/CommandLine/GenerateCommandLineParametersTest.cs b/src/ChangeLog.Test/CommandLine/GenerateCommandLineParametersTest.cs
index 162c6853..ab9b4e69 100644
--- a/src/ChangeLog.Test/CommandLine/GenerateCommandLineParametersTest.cs
+++ b/src/ChangeLog.Test/CommandLine/GenerateCommandLineParametersTest.cs
@@ -65,7 +65,7 @@ public void CommandLineParameters_returns_a_rooted_output_path()
         [Theory]
         [InlineData(null)]
         [InlineData("")]
-        public void CommandLineParameters_returns_null_if_output_path_is_null_or_empty(string outputPath)
+        public void CommandLineParameters_returns_null_if_output_path_is_null_or_empty(string? outputPath)
         {
             // ARRANGE
             var sut = new GenerateCommandLineParameters()
diff --git a/src/ChangeLog.Test/CommandLine/GenerateCommandLineParametersValidatorTest.cs b/src/ChangeLog.Test/CommandLine/GenerateCommandLineParametersValidatorTest.cs
index 1db7a5c3..c4b5001c 100644
--- a/src/ChangeLog.Test/CommandLine/GenerateCommandLineParametersValidatorTest.cs
+++ b/src/ChangeLog.Test/CommandLine/GenerateCommandLineParametersValidatorTest.cs
@@ -13,12 +13,12 @@ public class GenerateCommandLineParametersValidatorTest
         [Theory]
         [InlineData("")]
         [InlineData(null)]
-        public void RepositoryPath_may_be_empty(string repositoryPath)
+        public void RepositoryPath_may_be_empty(string? repositoryPath)
         {
             // ARRANGE
             var parameters = new GenerateCommandLineParameters()
             {
-                RepositoryPath = repositoryPath
+                RepositoryPath = repositoryPath!
             };
 
             var validator = new GenerateCommandLineParametersValidator();
@@ -86,7 +86,7 @@ public void RepositoryPath_must_exists()
         [Theory]
         [InlineData("")]
         [InlineData(null)]
-        public void CurrentVersion_may_be_empty(string value)
+        public void CurrentVersion_may_be_empty(string? value)
         {
             // ARRANGE
             using var repositoryDirectory = new TemporaryDirectory();
@@ -136,7 +136,7 @@ public void CurrentVersion_must_be_a_valid_version_if_parameter_is_set(string ve
         [Theory]
         [InlineData("")]
         [InlineData(null)]
-        public void VersionRange_may_be_empty(string value)
+        public void VersionRange_may_be_empty(string? value)
         {
             // ARRANGE
             using var repositoryDirectory = new TemporaryDirectory();
@@ -186,7 +186,7 @@ public void VersionRange_must_be_a_valid_version_range_if_parameter_is_set(strin
         [Theory]
         [InlineData("")]
         [InlineData(null)]
-        public void GitHubAccessToken_may_be_empty(string value)
+        public void GitHubAccessToken_may_be_empty(string? value)
         {
             // ARRANGE
             using var repositoryDirectory = new TemporaryDirectory();
@@ -209,7 +209,7 @@ public void GitHubAccessToken_may_be_empty(string value)
         [Theory]
         [InlineData("")]
         [InlineData(null)]
-        public void GitLabAccessToken_may_be_empty(string value)
+        public void GitLabAccessToken_may_be_empty(string? value)
         {
             // ARRANGE
             using var repositoryDirectory = new TemporaryDirectory();
@@ -232,7 +232,7 @@ public void GitLabAccessToken_may_be_empty(string value)
         [Theory]
         [InlineData("")]
         [InlineData(null)]
-        public void ConfigurationFilePath_may_be_empty(string path)
+        public void ConfigurationFilePath_may_be_empty(string? path)
         {
             // ARRANGE
             using var repositoryDirectory = new TemporaryDirectory();
diff --git a/src/ChangeLog.Test/Configuration/ConfigurationValidatorTest.cs b/src/ChangeLog.Test/Configuration/ConfigurationValidatorTest.cs
index 2c0a399a..cfd98ed9 100644
--- a/src/ChangeLog.Test/Configuration/ConfigurationValidatorTest.cs
+++ b/src/ChangeLog.Test/Configuration/ConfigurationValidatorTest.cs
@@ -137,7 +137,7 @@ public class VersionRange
             [Theory]
             [InlineData("")]
             [InlineData(null)]
-            public void Can_be_null_or_empty(string versionRange)
+            public void Can_be_null_or_empty(string? versionRange)
             {
                 // ARRANGE
                 var config = ChangeLogConfigurationLoader.GetDefaultConfiguration();
@@ -179,7 +179,7 @@ public class CurrentVersion
             [Theory]
             [InlineData("")]
             [InlineData(null)]
-            public void Can_be_null_or_empty(string currentVersion)
+            public void Can_be_null_or_empty(string? currentVersion)
             {
                 // ARRANGE
                 var config = ChangeLogConfigurationLoader.GetDefaultConfiguration();
@@ -292,7 +292,7 @@ public class GitHub
                 [Theory]
                 [InlineData("")]
                 [InlineData(null)]
-                public void AccessToken_can_be_null_or_empty(string accessToken)
+                public void AccessToken_can_be_null_or_empty(string? accessToken)
                 {
                     // ARRANGE
                     var config = ChangeLogConfigurationLoader.GetDefaultConfiguration();
@@ -333,7 +333,7 @@ public void AccessToken_must_not_be_whitespace(string accessToken)
                 [InlineData(null)]
                 [InlineData("\t")]
                 [InlineData("  ")]
-                public void RemoteName_must_not_be_null_or_whitespace(string remoteName)
+                public void RemoteName_must_not_be_null_or_whitespace(string? remoteName)
                 {
                     // ARRANGE
                     var config = ChangeLogConfigurationLoader.GetDefaultConfiguration();
@@ -353,7 +353,7 @@ public void RemoteName_must_not_be_null_or_whitespace(string remoteName)
                 [Theory]
                 [InlineData("")]
                 [InlineData(null)]
-                public void Host_can_be_null_or_empty(string host)
+                public void Host_can_be_null_or_empty(string? host)
                 {
                     // ARRANGE
                     var config = ChangeLogConfigurationLoader.GetDefaultConfiguration();
@@ -392,7 +392,7 @@ public void Host_must_not_be_whitespace(string host)
                 [Theory]
                 [InlineData("")]
                 [InlineData(null)]
-                public void Owner_can_be_null_or_empty(string owner)
+                public void Owner_can_be_null_or_empty(string? owner)
                 {
                     // ARRANGE
                     var config = ChangeLogConfigurationLoader.GetDefaultConfiguration();
@@ -431,7 +431,7 @@ public void Owner_must_not_be_whitespace(string owner)
                 [Theory]
                 [InlineData("")]
                 [InlineData(null)]
-                public void Repository_can_be_null_or_empty(string repository)
+                public void Repository_can_be_null_or_empty(string? repository)
                 {
                     // ARRANGE
                     var config = ChangeLogConfigurationLoader.GetDefaultConfiguration();
@@ -473,7 +473,7 @@ public class GitLab
                 [Theory]
                 [InlineData("")]
                 [InlineData(null)]
-                public void AccessToken_can_be_null_or_empty(string accessToken)
+                public void AccessToken_can_be_null_or_empty(string? accessToken)
                 {
                     // ARRANGE
                     var config = ChangeLogConfigurationLoader.GetDefaultConfiguration();
@@ -514,7 +514,7 @@ public void AccessToken_must_not_be_whitespace(string accessToken)
                 [InlineData(null)]
                 [InlineData("\t")]
                 [InlineData("  ")]
-                public void RemoteName_must_not_be_null_or_whitespace(string remoteName)
+                public void RemoteName_must_not_be_null_or_whitespace(string? remoteName)
                 {
                     // ARRANGE
                     var config = ChangeLogConfigurationLoader.GetDefaultConfiguration();
@@ -534,7 +534,7 @@ public void RemoteName_must_not_be_null_or_whitespace(string remoteName)
                 [Theory]
                 [InlineData("")]
                 [InlineData(null)]
-                public void Host_can_be_null_or_empty(string host)
+                public void Host_can_be_null_or_empty(string? host)
                 {
                     // ARRANGE
                     var config = ChangeLogConfigurationLoader.GetDefaultConfiguration();
@@ -573,7 +573,7 @@ public void Host_must_not_be_whitespace(string host)
                 [Theory]
                 [InlineData("")]
                 [InlineData(null)]
-                public void Namespace_can_be_null_or_empty(string @namespace)
+                public void Namespace_can_be_null_or_empty(string? @namespace)
                 {
                     // ARRANGE
                     var config = ChangeLogConfigurationLoader.GetDefaultConfiguration();
@@ -612,7 +612,7 @@ public void Namespace_must_not_be_whitespace(string @namespace)
                 [Theory]
                 [InlineData("")]
                 [InlineData(null)]
-                public void Project_can_be_null_or_empty(string project)
+                public void Project_can_be_null_or_empty(string? project)
                 {
                     // ARRANGE
                     var config = ChangeLogConfigurationLoader.GetDefaultConfiguration();
@@ -655,7 +655,7 @@ public class Filter
             [Theory]
             [InlineData(null)]
             [InlineData("")]
-            public void Type_expression_can_be_null_or_empty(string filterType)
+            public void Type_expression_can_be_null_or_empty(string? filterType)
             {
                 // ARRANGE
                 var config = ChangeLogConfigurationLoader.GetDefaultConfiguration();
@@ -663,14 +663,14 @@ public void Type_expression_can_be_null_or_empty(string filterType)
                 {
                     new ChangeLogConfiguration.FilterExpressionConfiguration()
                     {
-                        Type = filterType
+                        Type = filterType!
                     }
                 };
                 config.Filter.Exclude = new[]
                 {
                     new ChangeLogConfiguration.FilterExpressionConfiguration()
                     {
-                        Type = filterType
+                        Type = filterType!
                     }
                 };
 
@@ -721,7 +721,7 @@ public void Type_expression_must_not_be_whitespace(string filterType)
             [Theory]
             [InlineData(null)]
             [InlineData("")]
-            public void Scope_expression_can_be_null_or_empty(string filterType)
+            public void Scope_expression_can_be_null_or_empty(string? filterType)
             {
                 // ARRANGE
                 var config = ChangeLogConfigurationLoader.GetDefaultConfiguration();
@@ -729,14 +729,14 @@ public void Scope_expression_can_be_null_or_empty(string filterType)
                 {
                     new ChangeLogConfiguration.FilterExpressionConfiguration()
                 {
-                    Scope = filterType
+                    Scope = filterType!
                 }
                 };
                 config.Filter.Exclude = new[]
                 {
                     new ChangeLogConfiguration.FilterExpressionConfiguration()
                 {
-                    Scope = filterType
+                    Scope = filterType!
                 }
                 };
 
@@ -954,12 +954,12 @@ public void Provider_must_be_defined_value()
             [InlineData("")]
             [InlineData("\t")]
             [InlineData("  ")]
-            public void GitNotesNamespace_must_not_be_null_or_whitespace_when_message_overrides_are_enabled(string gitNotesNamespace)
+            public void GitNotesNamespace_must_not_be_null_or_whitespace_when_message_overrides_are_enabled(string? gitNotesNamespace)
             {
                 // ARRANGE
                 var config = ChangeLogConfigurationLoader.GetDefaultConfiguration();
                 config.MessageOverrides.Enabled = true;
-                config.MessageOverrides.GitNotesNamespace = gitNotesNamespace;
+                config.MessageOverrides.GitNotesNamespace = gitNotesNamespace!;
 
                 var sut = new ConfigurationValidator();
 
@@ -986,13 +986,13 @@ public void GitNotesNamespace_must_not_be_null_or_whitespace_when_message_overri
             [InlineData(true, ChangeLogConfiguration.MessageOverrideProvider.FileSystem, "")]
             [InlineData(true, ChangeLogConfiguration.MessageOverrideProvider.FileSystem, "\t")]
             [InlineData(true, ChangeLogConfiguration.MessageOverrideProvider.FileSystem, "  ")]
-            public void GitNotesNamespace_may_be_null_or_whitespace_when_message_overrides_are_disabled_or_another_provider_is_used(bool enabled, ChangeLogConfiguration.MessageOverrideProvider provider, string gitNotesNamespace)
+            public void GitNotesNamespace_may_be_null_or_whitespace_when_message_overrides_are_disabled_or_another_provider_is_used(bool enabled, ChangeLogConfiguration.MessageOverrideProvider provider, string? gitNotesNamespace)
             {
                 // ARRANGE
                 var config = ChangeLogConfigurationLoader.GetDefaultConfiguration();
                 config.MessageOverrides.Enabled = enabled;
                 config.MessageOverrides.Provider = provider;
-                config.MessageOverrides.GitNotesNamespace = gitNotesNamespace;
+                config.MessageOverrides.GitNotesNamespace = gitNotesNamespace!;
 
                 var sut = new ConfigurationValidator();
 
@@ -1009,13 +1009,13 @@ public void GitNotesNamespace_may_be_null_or_whitespace_when_message_overrides_a
             [InlineData("")]
             [InlineData("\t")]
             [InlineData("  ")]
-            public void SourceDirectoryPath_must_not_be_null_or_whitespace_when_message_overrides_are_enabled(string sourceDirectoryPath)
+            public void SourceDirectoryPath_must_not_be_null_or_whitespace_when_message_overrides_are_enabled(string? sourceDirectoryPath)
             {
                 // ARRANGE
                 var config = ChangeLogConfigurationLoader.GetDefaultConfiguration();
                 config.MessageOverrides.Enabled = true;
                 config.MessageOverrides.Provider = ChangeLogConfiguration.MessageOverrideProvider.FileSystem;
-                config.MessageOverrides.SourceDirectoryPath = sourceDirectoryPath;
+                config.MessageOverrides.SourceDirectoryPath = sourceDirectoryPath!;
 
                 var sut = new ConfigurationValidator();
 
@@ -1042,13 +1042,13 @@ public void SourceDirectoryPath_must_not_be_null_or_whitespace_when_message_over
             [InlineData(false, ChangeLogConfiguration.MessageOverrideProvider.FileSystem, "")]
             [InlineData(false, ChangeLogConfiguration.MessageOverrideProvider.FileSystem, "\t")]
             [InlineData(false, ChangeLogConfiguration.MessageOverrideProvider.FileSystem, "  ")]
-            public void SourceDirectoryPath_may_be_null_or_whitespace_when_message_overrides_are_disabled_or_another_provider_is_used(bool enabled, ChangeLogConfiguration.MessageOverrideProvider provider, string sourceDirectoryPath)
+            public void SourceDirectoryPath_may_be_null_or_whitespace_when_message_overrides_are_disabled_or_another_provider_is_used(bool enabled, ChangeLogConfiguration.MessageOverrideProvider provider, string? sourceDirectoryPath)
             {
                 // ARRANGE
                 var config = ChangeLogConfigurationLoader.GetDefaultConfiguration();
                 config.MessageOverrides.Enabled = enabled;
                 config.MessageOverrides.Provider = provider;
-                config.MessageOverrides.SourceDirectoryPath = sourceDirectoryPath;
+                config.MessageOverrides.SourceDirectoryPath = sourceDirectoryPath!;
 
                 var sut = new ConfigurationValidator();
 
diff --git a/src/ChangeLog.Test/ConventionalCommits/CommitMessageFooterNameTest.cs b/src/ChangeLog.Test/ConventionalCommits/CommitMessageFooterNameTest.cs
index ed0b67ad..1e5e1874 100644
--- a/src/ChangeLog.Test/ConventionalCommits/CommitMessageFooterNameTest.cs
+++ b/src/ChangeLog.Test/ConventionalCommits/CommitMessageFooterNameTest.cs
@@ -62,9 +62,9 @@ public class CommitMessageFooterNameTest : EqualityTest<CommitMessageFooterName,
         [InlineData("")]
         [InlineData("  ")]
         [InlineData("\t")]
-        public void Key_must_not_be_null_or_whitespace(string key)
+        public void Key_must_not_be_null_or_whitespace(string? key)
         {
-            Assert.Throws<ArgumentException>(() => new CommitMessageFooterName(key));
+            Assert.Throws<ArgumentException>(() => new CommitMessageFooterName(key!));
         }
 
         [Fact]
diff --git a/src/ChangeLog.Test/ConventionalCommits/CommitMessageFooterTest.cs b/src/ChangeLog.Test/ConventionalCommits/CommitMessageFooterTest.cs
index 9bff0e0f..29218048 100644
--- a/src/ChangeLog.Test/ConventionalCommits/CommitMessageFooterTest.cs
+++ b/src/ChangeLog.Test/ConventionalCommits/CommitMessageFooterTest.cs
@@ -41,9 +41,9 @@ public class CommitMessageFooterTest : EqualityTest<CommitMessageFooter, CommitM
         [InlineData("")]
         [InlineData("  ")]
         [InlineData("\t")]
-        public void Value_must_not_be_null_or_whitespace(string value)
+        public void Value_must_not_be_null_or_whitespace(string? value)
         {
-            Assert.Throws<ArgumentException>(() => new CommitMessageFooter(new CommitMessageFooterName("name"), value));
+            Assert.Throws<ArgumentException>(() => new CommitMessageFooter(new CommitMessageFooterName("name"), value!));
         }
     }
 }
diff --git a/src/ChangeLog.Test/ConventionalCommits/CommitMessageHeaderTest.cs b/src/ChangeLog.Test/ConventionalCommits/CommitMessageHeaderTest.cs
index eeb55131..0bc71abf 100644
--- a/src/ChangeLog.Test/ConventionalCommits/CommitMessageHeaderTest.cs
+++ b/src/ChangeLog.Test/ConventionalCommits/CommitMessageHeaderTest.cs
@@ -62,10 +62,10 @@ public class CommitMessageHeaderTest : EqualityTest<CommitMessageHeader, CommitM
         [InlineData("")]
         [InlineData("  ")]
         [InlineData("\t")]
-        public void Description_must_not_be_null_or_whitespace(string description)
+        public void Description_must_not_be_null_or_whitespace(string? description)
         {
-            Assert.Throws<ArgumentException>(() => new CommitMessageHeader(CommitType.Feature, description));
-            Assert.Throws<ArgumentException>(() => new CommitMessageHeader(CommitType.Feature, description, "someScope"));
+            Assert.Throws<ArgumentException>(() => new CommitMessageHeader(CommitType.Feature, description!));
+            Assert.Throws<ArgumentException>(() => new CommitMessageHeader(CommitType.Feature, description!, "someScope"));
         }
     }
 }
diff --git a/src/ChangeLog.Test/ConventionalCommits/CommitTypeTest.cs b/src/ChangeLog.Test/ConventionalCommits/CommitTypeTest.cs
index 70151392..0b604f23 100644
--- a/src/ChangeLog.Test/ConventionalCommits/CommitTypeTest.cs
+++ b/src/ChangeLog.Test/ConventionalCommits/CommitTypeTest.cs
@@ -28,9 +28,9 @@ public class CommitTypeTest : EqualityTest<CommitType, CommitTypeTest>, IEqualit
         [InlineData("")]
         [InlineData("  ")]
         [InlineData("\t")]
-        public void Type_must_not_be_null_or_whitespace(string type)
+        public void Type_must_not_be_null_or_whitespace(string? type)
         {
-            Assert.Throws<ArgumentException>(() => new CommitType(type));
+            Assert.Throws<ArgumentException>(() => new CommitType(type!));
         }
 
         [Theory]
diff --git a/src/ChangeLog.Test/E2E/E2ETests.cs b/src/ChangeLog.Test/E2E/E2ETests.cs
index c2e348bb..f4d7dba1 100644
--- a/src/ChangeLog.Test/E2E/E2ETests.cs
+++ b/src/ChangeLog.Test/E2E/E2ETests.cs
@@ -270,7 +270,7 @@ public async Task When_started_outside_of_a_git_repository_and_no_repository_pat
         [InlineData(new string[] { "changelog.settings.json", "custom.settings.json" }, "custom.settings.json", "custom.settings.json")]
         [InlineData(new string[] { ".config/changelog/settings.json", "custom.settings.json" }, "custom.settings.json", "custom.settings.json")]
         [InlineData(new string[] { "changelog.settings.json", ".config/changelog/settings.json", "custom.settings.json" }, "custom.settings.json", "custom.settings.json")]
-        public async Task The_expected_configuration_file_is_used(string[] configurationFilesOnDisk, string? configurationFileParameter, string expectedConfigurationFile)
+        public async Task The_expected_configuration_file_is_used(string[] configurationFilesOnDisk, string? configurationFileParameter, string? expectedConfigurationFile)
         {
             // ARRANGE
             using var temporaryDirectory = new TemporaryDirectory();
diff --git a/src/ChangeLog.Test/Filtering/FilterExpressionTest.cs b/src/ChangeLog.Test/Filtering/FilterExpressionTest.cs
index 1b4d8402..39b37d29 100644
--- a/src/ChangeLog.Test/Filtering/FilterExpressionTest.cs
+++ b/src/ChangeLog.Test/Filtering/FilterExpressionTest.cs
@@ -104,7 +104,7 @@ public void Type_must_not_be_whitespace(string type)
         [Theory]
         [InlineData(null)]
         [InlineData("")]
-        public void Type_may_be_null_or_empty(string type)
+        public void Type_may_be_null_or_empty(string? type)
         {
             _ = new FilterExpression(type, "*");
         }
@@ -120,7 +120,7 @@ public void Scope_must_not_be_whitespace(string scope)
         [Theory]
         [InlineData(null)]
         [InlineData("")]
-        public void Scope_may_be_null_or_empty(string scope)
+        public void Scope_may_be_null_or_empty(string? scope)
         {
             _ = new FilterExpression("*", scope);
         }
diff --git a/src/ChangeLog.Test/Git/GitAuthorTest.cs b/src/ChangeLog.Test/Git/GitAuthorTest.cs
index 99892f5a..9b4fe738 100644
--- a/src/ChangeLog.Test/Git/GitAuthorTest.cs
+++ b/src/ChangeLog.Test/Git/GitAuthorTest.cs
@@ -27,9 +27,9 @@ public class GitAuthorTest : EqualityTest<GitAuthor, GitAuthorTest>, IEqualityTe
         [InlineData("")]
         [InlineData("  ")]
         [InlineData("\t")]
-        public void Name_must_not_be_null_or_whitespace(string name)
+        public void Name_must_not_be_null_or_whitespace(string? name)
         {
-            Assert.Throws<ArgumentException>(() => new GitAuthor(name, "user@example.com"));
+            Assert.Throws<ArgumentException>(() => new GitAuthor(name!, "user@example.com"));
         }
 
         [Theory]
@@ -37,9 +37,9 @@ public void Name_must_not_be_null_or_whitespace(string name)
         [InlineData("")]
         [InlineData("  ")]
         [InlineData("\t")]
-        public void Email_must_not_be_null_or_whitespace(string email)
+        public void Email_must_not_be_null_or_whitespace(string? email)
         {
-            Assert.Throws<ArgumentException>(() => new GitAuthor("user", email));
+            Assert.Throws<ArgumentException>(() => new GitAuthor("user", email!));
         }
 
     }
diff --git a/src/ChangeLog.Test/Git/GitIdTest.cs b/src/ChangeLog.Test/Git/GitIdTest.cs
index 4774f860..225e6a96 100644
--- a/src/ChangeLog.Test/Git/GitIdTest.cs
+++ b/src/ChangeLog.Test/Git/GitIdTest.cs
@@ -46,12 +46,12 @@ public class GitIdTest : EqualityTest<GitId, GitIdTest>, IEqualityTestDataProvid
         [InlineData("8badf00d", "8BADF00D")]
         // Full id must start with abbreviated id
         [InlineData("abcd1234abcd1234abcd1234abcd1234abcd1234", "cde5678")]
-        public void Constructor_throws_ArgumentException_if_input_is_not_a_valid_full_and_abbreviated_git_object_id(string id, string abbreviatedId)
+        public void Constructor_throws_ArgumentException_if_input_is_not_a_valid_full_and_abbreviated_git_object_id(string? id, string? abbreviatedId)
         {
             // ARRANGE
 
             // ACT
-            var ex = Record.Exception(() => new GitId(id, abbreviatedId));
+            var ex = Record.Exception(() => new GitId(id!, abbreviatedId!));
 
             // ASSERT
             Assert.NotNull(ex);
diff --git a/src/ChangeLog.Test/Git/GitNoteTest.cs b/src/ChangeLog.Test/Git/GitNoteTest.cs
index cc212414..00f7c604 100644
--- a/src/ChangeLog.Test/Git/GitNoteTest.cs
+++ b/src/ChangeLog.Test/Git/GitNoteTest.cs
@@ -54,12 +54,12 @@ public void Target_must_not_be_null()
         [InlineData("")]
         [InlineData(" ")]
         [InlineData("\t")]
-        public void Namespace_must_not_be_null_or_whitespace(string @namespace)
+        public void Namespace_must_not_be_null_or_whitespace(string? @namespace)
         {
             // ARRANGE
 
             // ACT 
-            var ex = Record.Exception(() => new GitNote(TestGitIds.Id1, @namespace: @namespace, "message"));
+            var ex = Record.Exception(() => new GitNote(TestGitIds.Id1, @namespace: @namespace!, "message"));
 
             // ASSERT
             var argumentException = Assert.IsType<ArgumentException>(ex);
diff --git a/src/ChangeLog.Test/Git/GitRemoteTest.cs b/src/ChangeLog.Test/Git/GitRemoteTest.cs
index bdc6ad81..dd6cdf3a 100644
--- a/src/ChangeLog.Test/Git/GitRemoteTest.cs
+++ b/src/ChangeLog.Test/Git/GitRemoteTest.cs
@@ -27,9 +27,9 @@ public class GitRemoteTest : EqualityTest<GitRemote, GitRemoteTest>, IEqualityTe
         [InlineData("")]
         [InlineData("  ")]
         [InlineData("\t")]
-        public void Name_must_not_be_null_or_whitespace(string name)
+        public void Name_must_not_be_null_or_whitespace(string? name)
         {
-            Assert.Throws<ArgumentException>(() => new GitRemote(name, "http://example.com"));
+            Assert.Throws<ArgumentException>(() => new GitRemote(name!, "http://example.com"));
         }
 
         [Theory]
@@ -37,9 +37,9 @@ public void Name_must_not_be_null_or_whitespace(string name)
         [InlineData("")]
         [InlineData("  ")]
         [InlineData("\t")]
-        public void Url_must_not_be_null_or_whitespace(string url)
+        public void Url_must_not_be_null_or_whitespace(string? url)
         {
-            Assert.Throws<ArgumentException>(() => new GitRemote("origin", url));
+            Assert.Throws<ArgumentException>(() => new GitRemote("origin", url!));
         }
     }
 }
diff --git a/src/ChangeLog.Test/Git/GitRepositoryTest.cs b/src/ChangeLog.Test/Git/GitRepositoryTest.cs
index 74fd1e2d..78a953ba 100644
--- a/src/ChangeLog.Test/Git/GitRepositoryTest.cs
+++ b/src/ChangeLog.Test/Git/GitRepositoryTest.cs
@@ -46,9 +46,9 @@ public Task DisposeAsync()
         [InlineData("")]
         [InlineData("  ")]
         [InlineData("\t")]
-        public void Repository_path_must_not_be_null_or_whitespace(string repositoryPath)
+        public void Repository_path_must_not_be_null_or_whitespace(string? repositoryPath)
         {
-            Assert.Throws<ArgumentException>(() => new GitRepository(repositoryPath));
+            Assert.Throws<ArgumentException>(() => new GitRepository(repositoryPath!));
         }
 
         [Fact]
@@ -263,13 +263,13 @@ public async Task GetCommits_returns_the_expected_commits_05()
         [InlineData("")]
         [InlineData(" ")]
         [InlineData("\t")]
-        public void TryGetCommit_throws_ArgumentException_if_id_is_null_or_whitespace(string id)
+        public void TryGetCommit_throws_ArgumentException_if_id_is_null_or_whitespace(string? id)
         {
             // ARRANGE
             using var sut = new GitRepository(m_WorkingDirectory);
 
             // ACT 
-            var ex = Record.Exception(() => sut.TryGetCommit(id));
+            var ex = Record.Exception(() => sut.TryGetCommit(id!));
 
             // ASSERT
             Assert.NotNull(ex);
diff --git a/src/ChangeLog.Test/Git/GitTagTest.cs b/src/ChangeLog.Test/Git/GitTagTest.cs
index 0058903c..13028055 100644
--- a/src/ChangeLog.Test/Git/GitTagTest.cs
+++ b/src/ChangeLog.Test/Git/GitTagTest.cs
@@ -35,9 +35,9 @@ public class GitTagTest : EqualityTest<GitTag, GitTagTest>, IEqualityTestDataPro
         [InlineData("")]
         [InlineData("  ")]
         [InlineData("\t")]
-        public void Name_must_not_be_null_or_whitespace(string name)
+        public void Name_must_not_be_null_or_whitespace(string? name)
         {
-            Assert.Throws<ArgumentException>(() => new GitTag(name, TestGitIds.Id1));
+            Assert.Throws<ArgumentException>(() => new GitTag(name!, TestGitIds.Id1));
         }
 
         [Fact]
diff --git a/src/ChangeLog.Test/Grynwald.ChangeLog.Test.csproj b/src/ChangeLog.Test/Grynwald.ChangeLog.Test.csproj
index 2f842a94..9ee23d52 100644
--- a/src/ChangeLog.Test/Grynwald.ChangeLog.Test.csproj
+++ b/src/ChangeLog.Test/Grynwald.ChangeLog.Test.csproj
@@ -14,7 +14,7 @@
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
     <PackageReference Include="Moq" Version="4.18.4" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
-    <PackageReference Include="xunit" Version="2.5.1" />
+    <PackageReference Include="xunit" Version="2.6.2" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.5.4" />
     <PackageReference Include="Xunit.Combinatorial" Version="1.6.24" />
     <PackageReference Include="NetArchTest.Rules" Version="1.3.2" />
diff --git a/src/ChangeLog.Test/Integrations/GitHub/GitHubClientFactoryTest.cs b/src/ChangeLog.Test/Integrations/GitHub/GitHubClientFactoryTest.cs
index 5cd07617..6c4f7f3b 100644
--- a/src/ChangeLog.Test/Integrations/GitHub/GitHubClientFactoryTest.cs
+++ b/src/ChangeLog.Test/Integrations/GitHub/GitHubClientFactoryTest.cs
@@ -47,7 +47,7 @@ public void CreateClient_adds_an_access_token_if_token_is_configured()
         [Theory]
         [InlineData("")]
         [InlineData(null)]
-        public void CreateClient_succeeds_if_no_access_token_is_configured(string accessToken)
+        public void CreateClient_succeeds_if_no_access_token_is_configured(string? accessToken)
         {
             // ARRANGE
             var configuration = new ChangeLogConfiguration();
diff --git a/src/ChangeLog.Test/Integrations/GitHub/GitHubProjectInfoTest.cs b/src/ChangeLog.Test/Integrations/GitHub/GitHubProjectInfoTest.cs
index 81962185..34302dd5 100644
--- a/src/ChangeLog.Test/Integrations/GitHub/GitHubProjectInfoTest.cs
+++ b/src/ChangeLog.Test/Integrations/GitHub/GitHubProjectInfoTest.cs
@@ -53,9 +53,9 @@ public class GitHubProjectInfoTest : EqualityTest<GitHubProjectInfo, GitHubProje
         [InlineData("")]
         [InlineData("  ")]
         [InlineData("\t")]
-        public void Host_must_not_be_null_or_whitespace(string host)
+        public void Host_must_not_be_null_or_whitespace(string? host)
         {
-            Assert.Throws<ArgumentException>(() => new GitHubProjectInfo(host, "user", "repo"));
+            Assert.Throws<ArgumentException>(() => new GitHubProjectInfo(host!, "user", "repo"));
         }
 
         [Theory]
@@ -63,9 +63,9 @@ public void Host_must_not_be_null_or_whitespace(string host)
         [InlineData("")]
         [InlineData("  ")]
         [InlineData("\t")]
-        public void User_must_not_be_null_or_whitespace(string user)
+        public void User_must_not_be_null_or_whitespace(string? user)
         {
-            Assert.Throws<ArgumentException>(() => new GitHubProjectInfo("example.com", user, "repo"));
+            Assert.Throws<ArgumentException>(() => new GitHubProjectInfo("example.com", user!, "repo"));
         }
 
         [Theory]
@@ -73,9 +73,9 @@ public void User_must_not_be_null_or_whitespace(string user)
         [InlineData("")]
         [InlineData("  ")]
         [InlineData("\t")]
-        public void Project_must_not_be_null_or_whitespace(string project)
+        public void Project_must_not_be_null_or_whitespace(string? project)
         {
-            Assert.Throws<ArgumentException>(() => new GitHubProjectInfo("example.com", "user", project));
+            Assert.Throws<ArgumentException>(() => new GitHubProjectInfo("example.com", "user", project!));
         }
     }
 }
diff --git a/src/ChangeLog.Test/Integrations/GitHub/GitHubReferenceTest.cs b/src/ChangeLog.Test/Integrations/GitHub/GitHubReferenceTest.cs
index 12884c18..d00a73aa 100644
--- a/src/ChangeLog.Test/Integrations/GitHub/GitHubReferenceTest.cs
+++ b/src/ChangeLog.Test/Integrations/GitHub/GitHubReferenceTest.cs
@@ -143,13 +143,13 @@ public void TryParse_succeeds_for_parsable_references(string input, string curre
             [InlineData("GH-xyz")]
             [InlineData("#1 2 3")]
             [InlineData("GH-1 2 3")]
-            public void TryParse_fails_for_invalid_references(string input)
+            public void TryParse_fails_for_invalid_references(string? input)
             {
                 // ARRANGE
                 var currentProject = new GitHubProjectInfo("example.com", "owner", "repo");
 
                 // ACT 
-                var success = GitHubReference.TryParse(input, currentProject, out var result);
+                var success = GitHubReference.TryParse(input!, currentProject, out var result);
 
                 // ASSERT
                 Assert.False(success);
diff --git a/src/ChangeLog.Test/Integrations/GitHub/GitHubReferenceTextElementTest.cs b/src/ChangeLog.Test/Integrations/GitHub/GitHubReferenceTextElementTest.cs
index 63110923..07720b83 100644
--- a/src/ChangeLog.Test/Integrations/GitHub/GitHubReferenceTextElementTest.cs
+++ b/src/ChangeLog.Test/Integrations/GitHub/GitHubReferenceTextElementTest.cs
@@ -14,13 +14,13 @@ public class GitHubReferenceTextElementTest
         [InlineData("")]
         [InlineData(" ")]
         [InlineData("\t")]
-        public void Text_must_not_be_null_or_whitespace(string text)
+        public void Text_must_not_be_null_or_whitespace(string? text)
         {
             // ARRANGE
 
             // ACT 
             var ex = Record.Exception(() => new GitHubReferenceTextElement(
-                text,
+                text!,
                 new("http://example.com"),
                 new("example.com", "owner", "repo"),
                 new(new("example.com", "owner", "repo"), 23)));
diff --git a/src/ChangeLog.Test/Integrations/GitHub/GitHubUrlParserTest.cs b/src/ChangeLog.Test/Integrations/GitHub/GitHubUrlParserTest.cs
index a41488da..cc018dac 100644
--- a/src/ChangeLog.Test/Integrations/GitHub/GitHubUrlParserTest.cs
+++ b/src/ChangeLog.Test/Integrations/GitHub/GitHubUrlParserTest.cs
@@ -18,9 +18,9 @@ public class GitHubUrlParserTest
         [InlineData("not-a-url")]
         [InlineData("http://github.com/owner/another-name/repo.git")] // to many segments in the path
         [InlineData("ftp://github.com/owner/repo.git")] // unsupported scheme
-        public void ParseRemoteUrl_throws_ArgumentException_for_invalid_input(string url)
+        public void ParseRemoteUrl_throws_ArgumentException_for_invalid_input(string? url)
         {
-            Assert.ThrowsAny<ArgumentException>(() => GitHubUrlParser.ParseRemoteUrl(url));
+            Assert.ThrowsAny<ArgumentException>(() => GitHubUrlParser.ParseRemoteUrl(url!));
         }
 
         [Theory]
@@ -50,9 +50,9 @@ public void ParseRemoteUrl_returns_the_expected_GitHubProjectInfo(string url, st
         [InlineData("not-a-url")]
         [InlineData("http://github.com/owner/another-name/repo.git")] // to many segments in the path
         [InlineData("ftp://github.com/owner/repo.git")] // unsupported scheme
-        public void TryParseRemoteUrl_returns_false_for_invalid_input(string url)
+        public void TryParseRemoteUrl_returns_false_for_invalid_input(string? url)
         {
-            Assert.False(GitHubUrlParser.TryParseRemoteUrl(url, out var uri));
+            Assert.False(GitHubUrlParser.TryParseRemoteUrl(url!, out var uri));
         }
 
         [Theory]
diff --git a/src/ChangeLog.Test/Integrations/GitLab/GitLabClientFactoryTest.cs b/src/ChangeLog.Test/Integrations/GitLab/GitLabClientFactoryTest.cs
index 9315cddb..c6b56631 100644
--- a/src/ChangeLog.Test/Integrations/GitLab/GitLabClientFactoryTest.cs
+++ b/src/ChangeLog.Test/Integrations/GitLab/GitLabClientFactoryTest.cs
@@ -40,7 +40,7 @@ public void CreateClient_succeeds_if_an_access_token_is_configured()
         [Theory]
         [InlineData("")]
         [InlineData(null)]
-        public void CreateClient_succeeds_if_no_access_token_is_configured(string accessToken)
+        public void CreateClient_succeeds_if_no_access_token_is_configured(string? accessToken)
         {
             // ARRANGE
             var configuration = new ChangeLogConfiguration();
diff --git a/src/ChangeLog.Test/Integrations/GitLab/GitLabProjectInfoTest.cs b/src/ChangeLog.Test/Integrations/GitLab/GitLabProjectInfoTest.cs
index 11d0a3ce..049d171f 100644
--- a/src/ChangeLog.Test/Integrations/GitLab/GitLabProjectInfoTest.cs
+++ b/src/ChangeLog.Test/Integrations/GitLab/GitLabProjectInfoTest.cs
@@ -121,9 +121,9 @@ public class GitLabProjectInfoTest : EqualityTest<GitLabProjectInfo, GitLabProje
         [InlineData("")]
         [InlineData("  ")]
         [InlineData("\t")]
-        public void Host_must_not_be_null_or_whitespace(string host)
+        public void Host_must_not_be_null_or_whitespace(string? host)
         {
-            Assert.Throws<ArgumentException>(() => new GitLabProjectInfo(host, "user", "repo"));
+            Assert.Throws<ArgumentException>(() => new GitLabProjectInfo(host!, "user", "repo"));
         }
 
         [Theory]
@@ -131,9 +131,9 @@ public void Host_must_not_be_null_or_whitespace(string host)
         [InlineData("")]
         [InlineData("  ")]
         [InlineData("\t")]
-        public void Namespace_must_not_be_null_or_whitespace(string @namespace)
+        public void Namespace_must_not_be_null_or_whitespace(string? @namespace)
         {
-            Assert.Throws<ArgumentException>(() => new GitLabProjectInfo("example.com", @namespace, "repo"));
+            Assert.Throws<ArgumentException>(() => new GitLabProjectInfo("example.com", @namespace!, "repo"));
         }
 
         [Theory]
@@ -141,9 +141,9 @@ public void Namespace_must_not_be_null_or_whitespace(string @namespace)
         [InlineData("")]
         [InlineData("  ")]
         [InlineData("\t")]
-        public void Project_must_not_be_null_or_whitespace(string project)
+        public void Project_must_not_be_null_or_whitespace(string? project)
         {
-            Assert.Throws<ArgumentException>(() => new GitLabProjectInfo("example.com", "user", project));
+            Assert.Throws<ArgumentException>(() => new GitLabProjectInfo("example.com", "user", project!));
         }
     }
 }
diff --git a/src/ChangeLog.Test/Integrations/GitLab/GitLabReferenceTest.cs b/src/ChangeLog.Test/Integrations/GitLab/GitLabReferenceTest.cs
index 02ba49cf..170f712b 100644
--- a/src/ChangeLog.Test/Integrations/GitLab/GitLabReferenceTest.cs
+++ b/src/ChangeLog.Test/Integrations/GitLab/GitLabReferenceTest.cs
@@ -201,13 +201,13 @@ public void TryParse_returns_expected_reference(string input, string currentName
             [InlineData("Not a/reference#xyz")]
             [InlineData("#xyz")]
             [InlineData("#1 2 3")]
-            public void TryParse_fails_for_invalid_references(string input)
+            public void TryParse_fails_for_invalid_references(string? input)
             {
                 // ARRANGE
                 var currentProject = new GitLabProjectInfo("example.com", "namespace", "project");
 
                 // ACT 
-                var success = GitLabReference.TryParse(input, currentProject, out var result);
+                var success = GitLabReference.TryParse(input!, currentProject, out var result);
 
                 // ASSERT
                 Assert.False(success);
diff --git a/src/ChangeLog.Test/Integrations/GitLab/GitLabReferenceTextElementTest.cs b/src/ChangeLog.Test/Integrations/GitLab/GitLabReferenceTextElementTest.cs
index 7a60203c..06cd1d43 100644
--- a/src/ChangeLog.Test/Integrations/GitLab/GitLabReferenceTextElementTest.cs
+++ b/src/ChangeLog.Test/Integrations/GitLab/GitLabReferenceTextElementTest.cs
@@ -16,13 +16,13 @@ public class Constructor
             [InlineData("")]
             [InlineData(" ")]
             [InlineData("\t")]
-            public void Text_must_not_be_null_or_whitespace(string text)
+            public void Text_must_not_be_null_or_whitespace(string? text)
             {
                 // ARRANGE
 
                 // ACT 
                 var ex = Record.Exception(() => new GitLabReferenceTextElement(
-                    text,
+                    text!,
                     new("http://example.com"),
                     new("example.com", "namespace", "project"),
                     new(new("example.com", "namespace", "project"), GitLabReferenceType.Issue, 23)));
diff --git a/src/ChangeLog.Test/Integrations/GitLab/GitLabUrlParserTest.cs b/src/ChangeLog.Test/Integrations/GitLab/GitLabUrlParserTest.cs
index 4715437d..4e060a6c 100644
--- a/src/ChangeLog.Test/Integrations/GitLab/GitLabUrlParserTest.cs
+++ b/src/ChangeLog.Test/Integrations/GitLab/GitLabUrlParserTest.cs
@@ -18,9 +18,9 @@ public class GitLabUrlParserTest
         [InlineData("ftp://gitlab.com/owner/repo.git")] // unsupported scheme
         [InlineData("http://gitlab.com")]               // missing project path
         [InlineData("http://gitlab.com/user")]          // missing project name
-        public void ParseRemoteUrl_throws_ArgumentException_for_invalid_input(string url)
+        public void ParseRemoteUrl_throws_ArgumentException_for_invalid_input(string? url)
         {
-            Assert.ThrowsAny<ArgumentException>(() => GitLabUrlParser.ParseRemoteUrl(url));
+            Assert.ThrowsAny<ArgumentException>(() => GitLabUrlParser.ParseRemoteUrl(url!));
         }
 
         [Theory]
@@ -52,9 +52,9 @@ public void ParseRemoteUrl_returns_the_expected_GitLabProjectInfo(string remoteU
         [InlineData("ftp://gitlab.com/owner/repo.git")] // unsupported scheme
         [InlineData("http://gitlab.com")]               // missing project path
         [InlineData("http://gitlab.com/user")]          // missing project name
-        public void TryParseRemoteUrl_returns_false_for_invalid_input(string url)
+        public void TryParseRemoteUrl_returns_false_for_invalid_input(string? url)
         {
-            Assert.False(GitLabUrlParser.TryParseRemoteUrl(url, out var uri));
+            Assert.False(GitLabUrlParser.TryParseRemoteUrl(url!, out var uri));
         }
 
         [Theory]
diff --git a/src/ChangeLog.Test/Model/Text/ChangeLogEntryReferenceTextElementTest.cs b/src/ChangeLog.Test/Model/Text/ChangeLogEntryReferenceTextElementTest.cs
index 4ee6b475..aec3445e 100644
--- a/src/ChangeLog.Test/Model/Text/ChangeLogEntryReferenceTextElementTest.cs
+++ b/src/ChangeLog.Test/Model/Text/ChangeLogEntryReferenceTextElementTest.cs
@@ -14,13 +14,13 @@ public class ChangeLogEntryReferenceTextElementTest : TestBase
         [InlineData("")]
         [InlineData(" ")]
         [InlineData("\t")]
-        public void Text_must_not_be_null_or_whitespace(string text)
+        public void Text_must_not_be_null_or_whitespace(string? text)
         {
             // ARRANGE
             var entry = GetChangeLogEntry();
 
             // ACT 
-            var ex = Record.Exception(() => new ChangeLogEntryReferenceTextElement(text, entry));
+            var ex = Record.Exception(() => new ChangeLogEntryReferenceTextElement(text!, entry));
 
             // ASSERT
             var argumentException = Assert.IsType<ArgumentException>(ex);
diff --git a/src/ChangeLog.Test/Model/Text/CommitReferenceTextElementTest.cs b/src/ChangeLog.Test/Model/Text/CommitReferenceTextElementTest.cs
index 50e83d38..e10fcc89 100644
--- a/src/ChangeLog.Test/Model/Text/CommitReferenceTextElementTest.cs
+++ b/src/ChangeLog.Test/Model/Text/CommitReferenceTextElementTest.cs
@@ -15,12 +15,12 @@ public class CommitReferenceTextElementTest
         [InlineData("")]
         [InlineData(" ")]
         [InlineData("\t")]
-        public void Text_must_not_be_null_or_whitespace(string text)
+        public void Text_must_not_be_null_or_whitespace(string? text)
         {
             // ARRANGE
 
             // ACT 
-            var ex = Record.Exception(() => new CommitReferenceTextElement(text, TestGitIds.Id1));
+            var ex = Record.Exception(() => new CommitReferenceTextElement(text!, TestGitIds.Id1));
 
             // ASSERT
             var argumentException = Assert.IsType<ArgumentException>(ex);
diff --git a/src/ChangeLog.Test/Model/Text/CommitReferenceTextElementWithWebLinkTest.cs b/src/ChangeLog.Test/Model/Text/CommitReferenceTextElementWithWebLinkTest.cs
index 6604098d..222bbaca 100644
--- a/src/ChangeLog.Test/Model/Text/CommitReferenceTextElementWithWebLinkTest.cs
+++ b/src/ChangeLog.Test/Model/Text/CommitReferenceTextElementWithWebLinkTest.cs
@@ -17,12 +17,12 @@ public class CommitReferenceTextElementWithWebLinkTest
         [InlineData("")]
         [InlineData(" ")]
         [InlineData("\t")]
-        public void Text_must_not_be_null_or_whitespace(string text)
+        public void Text_must_not_be_null_or_whitespace(string? text)
         {
             // ARRANGE
 
             // ACT 
-            var ex = Record.Exception(() => new CommitReferenceTextElementWithWebLink(text, TestGitIds.Id1, new Uri("http://example.com")));
+            var ex = Record.Exception(() => new CommitReferenceTextElementWithWebLink(text!, TestGitIds.Id1, new Uri("http://example.com")));
 
             // ASSERT
             var argumentException = Assert.IsType<ArgumentException>(ex);
diff --git a/src/ChangeLog.Test/Model/Text/PlainTextElementTest.cs b/src/ChangeLog.Test/Model/Text/PlainTextElementTest.cs
index 4ec0770b..fd91716f 100644
--- a/src/ChangeLog.Test/Model/Text/PlainTextElementTest.cs
+++ b/src/ChangeLog.Test/Model/Text/PlainTextElementTest.cs
@@ -14,12 +14,12 @@ public class PlainTextElementTest
         [InlineData("")]
         [InlineData(" ")]
         [InlineData("\t")]
-        public void Text_must_not_be_null_or_whitespace(string text)
+        public void Text_must_not_be_null_or_whitespace(string? text)
         {
             // ARRANGE
 
             // ACT 
-            var ex = Record.Exception(() => new PlainTextElement(text));
+            var ex = Record.Exception(() => new PlainTextElement(text!));
 
             // ASSERT
             var argumentException = Assert.IsType<ArgumentException>(ex);
diff --git a/src/ChangeLog.Test/Model/Text/WebLinkTextElementTest.cs b/src/ChangeLog.Test/Model/Text/WebLinkTextElementTest.cs
index ea486057..cae8f8ab 100644
--- a/src/ChangeLog.Test/Model/Text/WebLinkTextElementTest.cs
+++ b/src/ChangeLog.Test/Model/Text/WebLinkTextElementTest.cs
@@ -14,12 +14,12 @@ public class WebLinkTextElementTest
         [InlineData("")]
         [InlineData(" ")]
         [InlineData("\t")]
-        public void Text_must_not_be_null_or_whitespace(string text)
+        public void Text_must_not_be_null_or_whitespace(string? text)
         {
             // ARRANGE
 
             // ACT 
-            var ex = Record.Exception(() => new WebLinkTextElement(text, new Uri("https://example.com")));
+            var ex = Record.Exception(() => new WebLinkTextElement(text!, new Uri("https://example.com")));
 
             // ASSERT
             var argumentException = Assert.IsType<ArgumentException>(ex);
diff --git a/src/ChangeLog.Test/Tasks/FilterVersionsTaskTest.cs b/src/ChangeLog.Test/Tasks/FilterVersionsTaskTest.cs
index 30d8538f..cd048c20 100644
--- a/src/ChangeLog.Test/Tasks/FilterVersionsTaskTest.cs
+++ b/src/ChangeLog.Test/Tasks/FilterVersionsTaskTest.cs
@@ -27,7 +27,7 @@ public FilterVersionsTaskTest(ITestOutputHelper testOutputHelper)
         [Theory]
         [InlineData("")]
         [InlineData(null)]
-        public async Task Run_has_no_effect_when_the_version_range_setting_is_null_or_empty(string versionRange)
+        public async Task Run_has_no_effect_when_the_version_range_setting_is_null_or_empty(string? versionRange)
         {
             // ARRANGE
             var config = new ChangeLogConfiguration() { VersionRange = versionRange };
diff --git a/src/ChangeLog.Test/Tasks/LoadCurrentVersionTaskTest.cs b/src/ChangeLog.Test/Tasks/LoadCurrentVersionTaskTest.cs
index f023d14c..b740dad0 100644
--- a/src/ChangeLog.Test/Tasks/LoadCurrentVersionTaskTest.cs
+++ b/src/ChangeLog.Test/Tasks/LoadCurrentVersionTaskTest.cs
@@ -72,7 +72,7 @@ public void Repository_must_not_be_null()
         [Theory]
         [InlineData("")]
         [InlineData(null)]
-        public async Task Task_is_skipped_if_current_version_is_not_set(string currentVersion)
+        public async Task Task_is_skipped_if_current_version_is_not_set(string? currentVersion)
         {
             // ARRANGE
             var config = new ChangeLogConfiguration()
diff --git a/src/ChangeLog.Test/Templates/ModelExtensionsTest.cs b/src/ChangeLog.Test/Templates/ModelExtensionsTest.cs
index 89cd296e..bb6a924c 100644
--- a/src/ChangeLog.Test/Templates/ModelExtensionsTest.cs
+++ b/src/ChangeLog.Test/Templates/ModelExtensionsTest.cs
@@ -16,7 +16,7 @@ public class ModelExtensionsTest : TestBase
         [Theory]
         [InlineData(null)]
         [InlineData("")]
-        public void GetScopeDisplayName_returns_scope_if_scope_is_null_or_empty(string scope)
+        public void GetScopeDisplayName_returns_scope_if_scope_is_null_or_empty(string? scope)
         {
             // ARRANGE
             var changeLogEntry = GetChangeLogEntry(scope: scope);
@@ -56,7 +56,7 @@ public void GetScopeDisplayName_returns_expected_display_name(string configuredS
         [InlineData("\t")]
         [InlineData("  ")]
         [InlineData(null)]
-        public void GetScopeDisplayName_returns_scope_if_display_name_is_empty(string displayName)
+        public void GetScopeDisplayName_returns_scope_if_display_name_is_empty(string? displayName)
         {
             // ARRANGE
             var config = new ChangeLogConfiguration()
@@ -148,7 +148,7 @@ public void GetFooterDisplayName_returns_footer_name_if_no_display_name_is_confi
         [InlineData("\t")]
         [InlineData("  ")]
         [InlineData(null)]
-        public void GetFooterDisplayName_returns_footer_name_if_display_name_is_empty(string configuredDisplayName)
+        public void GetFooterDisplayName_returns_footer_name_if_display_name_is_empty(string? configuredDisplayName)
         {
             // ARRANGE
             var footerName = "footerName";
diff --git a/src/ChangeLog.Test/packages.lock.json b/src/ChangeLog.Test/packages.lock.json
index 852efbcd..95a47a49 100644
--- a/src/ChangeLog.Test/packages.lock.json
+++ b/src/ChangeLog.Test/packages.lock.json
@@ -94,13 +94,13 @@
       },
       "xunit": {
         "type": "Direct",
-        "requested": "[2.5.1, )",
-        "resolved": "2.5.1",
-        "contentHash": "WJJ7Ruxv1INF4ySosVZ0fN1dGhzNBEdLLZoIVn4TPU8CbYgaxUebAL/VPaBneXGT3EDE2llsJ2cKzGkGeZSY4Q==",
+        "requested": "[2.6.2, )",
+        "resolved": "2.6.2",
+        "contentHash": "sErOyzTZBfgeLcdu5y3CkhCirZikCe9GwEv56jbQRjSa4FyI2tIHjfBRvlWqg7M78bfAGajrreH0IHnxrUOpVA==",
         "dependencies": {
-          "xunit.analyzers": "1.3.0",
-          "xunit.assert": "2.5.1",
-          "xunit.core": "[2.5.1]"
+          "xunit.analyzers": "1.6.0",
+          "xunit.assert": "2.6.2",
+          "xunit.core": "[2.6.2]"
         }
       },
       "Xunit.Combinatorial": {
@@ -1429,30 +1429,27 @@
       },
       "xunit.analyzers": {
         "type": "Transitive",
-        "resolved": "1.3.0",
-        "contentHash": "gSk+8RC6UZ6Fzx1OHoB2bPyENeg3WHIeJhB/hb4oZNN0pW0dwOuplJay6OnqFIvW8T37re/RB4PWpEvayWIO1Q=="
+        "resolved": "1.6.0",
+        "contentHash": "b/Wbrqr/bFvcjqAbYdJyCCvjz+PjjKMnoK/K6sbcCBu94pqAkB2vBAHFo87wNq2awsLPAuq5MA7q0XexyQ3mJQ=="
       },
       "xunit.assert": {
         "type": "Transitive",
-        "resolved": "2.5.1",
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