[dotnet] Enable Nullable Reference Types (SeleniumHQ#15354)

* [dotnet] Enable Nullable Reference Types

* Remove nullable enable

* fix build

* Add nullable handling to `executable_assembly.bzl`

* Fix format build

* Enable nullable on .NET Standard 2.0

* fix comment formatting

* whitespace

Author: RenderMichael

dotnet/private/executable_assembly.bzl

@@ -75,6 +75,7 @@ def create_executable_assembly(ctx, extra_srcs, extra_deps):
             internals_visible_to = None,
             internals_visible_to_cs = None,
             langversion = ctx.attr.langversion,
+            nullable = ctx.attr.nullable,
             resources = ctx.files.resources,
             srcs = ctx.files.srcs + extra_srcs,
             out = ctx.attr.out,
@@ -143,6 +144,9 @@ csharp_executable = rule(
         "langversion": attr.string(
             doc = "The version string for the C# language.",
         ),
+        "nullable": attr.string(
+            doc = "Enable nullable context, or nullable warnings.",
+        ),
         "resources": attr.label_list(
             doc = "A list of files to embed in the DLL as resources.",
             allow_files = True,

dotnet/src/webdriver/Alert.cs

@@ -20,8 +20,6 @@
 using System;
 using System.Collections.Generic;
 
-#nullable enable
-
 namespace OpenQA.Selenium
 {
     /// <summary>

dotnet/src/webdriver/BUILD.bazel

@@ -37,6 +37,7 @@ csharp_library(
         "WebDriver.Common.Tests",
     ],
     langversion = "12.0",
+    nullable = "enable",
     resources = [
         "//javascript/atoms/fragments:find-elements.js",
         "//javascript/atoms/fragments:is-displayed.js",
@@ -76,6 +77,7 @@ csharp_library(
         "WebDriver.Common.Tests",
     ],
     langversion = "12.0",
+    nullable = "enable",
     resources = [
         "//javascript/atoms/fragments:find-elements.js",
         "//javascript/atoms/fragments:is-displayed.js",
@@ -103,6 +105,7 @@ csharp_library(
     out = "WebDriver.StrongNamed",
     keyfile = "//dotnet:WebDriver.snk",
     langversion = "12.0",
+    nullable = "enable",
     resources = [
         "//javascript/atoms/fragments:find-elements.js",
         "//javascript/atoms/fragments:is-displayed.js",
@@ -140,6 +143,7 @@ csharp_library(
     ],
     keyfile = "//dotnet:WebDriver.snk",
     langversion = "12.0",
+    nullable = "enable",
     resources = [
         "//javascript/atoms/fragments:find-elements.js",
         "//javascript/atoms/fragments:is-displayed.js",

dotnet/src/webdriver/BiDi/BiDi.cs

@@ -22,8 +22,6 @@
 using OpenQA.Selenium.BiDi.Communication;
 using OpenQA.Selenium.BiDi.Communication.Transport;
 
-#nullable enable
-
 namespace OpenQA.Selenium.BiDi;
 
 public class BiDi : IAsyncDisposable

dotnet/src/webdriver/BiDi/BiDiException.cs

@@ -19,8 +19,6 @@
 
 using System;
 
-#nullable enable
-
 namespace OpenQA.Selenium.BiDi;
 
 public class BiDiException : Exception

dotnet/src/webdriver/BiDi/Communication/Broker.cs

@@ -30,8 +30,6 @@
 using System.Threading;
 using System.Threading.Tasks;
 
-#nullable enable
-
 namespace OpenQA.Selenium.BiDi.Communication;
 
 public class Broker : IAsyncDisposable

dotnet/src/webdriver/BiDi/Communication/Command.cs

@@ -17,8 +17,6 @@
 // under the License.
 // </copyright>
 
-#nullable enable
-
 namespace OpenQA.Selenium.BiDi.Communication;
 
 public abstract class Command

dotnet/src/webdriver/BiDi/Communication/CommandOptions.cs

@@ -19,8 +19,6 @@
 
 using System;
 
-#nullable enable
-
 namespace OpenQA.Selenium.BiDi.Communication;
 
 public record CommandOptions

dotnet/src/webdriver/BiDi/Communication/EventHandler.cs

@@ -22,8 +22,6 @@
 using System.Collections.Generic;
 using System.Threading.Tasks;
 
-#nullable enable
-
 namespace OpenQA.Selenium.BiDi.Communication;
 
 public abstract class EventHandler(string eventName, Type eventArgsType, IEnumerable<BrowsingContext>? contexts = null)

dotnet/src/webdriver/BiDi/Communication/Json/Converters/BrowserClientWindowConverter.cs

@@ -22,8 +22,6 @@
 using System.Text.Json;
 using System.Text.Json.Serialization;
 
-#nullable enable
-
 namespace OpenQA.Selenium.BiDi.Communication.Json.Converters;
 
 internal class BrowserClientWindowConverter : JsonConverter<ClientWindow>