[dotnet] Annotate nullability on DriverOptions

[RenderMichael]

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Description

Motivation and Context

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have read the contributing document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

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PR Type

Enhancement

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Description

• Annotated nullability for properties and methods in DriverOptions.

• Replaced backing fields with auto-implemented properties.

• Added nullability-related attributes and checks for improved safety.

• Refactored methods to align with nullability annotations.

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Changes walkthrough 📝

	Relevant files
Enhancement	DriverOptions.cs Annotate nullability and refactor `DriverOptions`                dotnet/src/webdriver/DriverOptions.cs Enabled nullable reference types with #nullable enable. Annotated properties and methods with nullable types and attributes. Replaced private backing fields with auto-implemented properties. Added null checks and exception handling for nullability compliance. +74/-120

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[qodo-merge-pro]

PR Reviewer Guide 🔍

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⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Null Reference The ToDictionary() method could throw a NullReferenceException if ToCapabilities() returns null, since the null check is only done after casting to IHasCapabilitiesDictionary. ICapabilities? capabilities = this.ToCapabilities(); if (capabilities is not IHasCapabilitiesDictionary desired)

[qodo-merge-pro]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Score
Possible issue	Add null check for parameter Add null check for capabilityName parameter in IsKnownCapabilityName method to prevent potential NullReferenceException when calling ContainsKey. dotnet/src/webdriver/DriverOptions.cs [402-405] -protected bool IsKnownCapabilityName(string capabilityName) +protected bool IsKnownCapabilityName(string? capabilityName) { - return this.knownCapabilityNames.ContainsKey(capabilityName); + return capabilityName != null && this.knownCapabilityNames.ContainsKey(capabilityName); } Apply this suggestion Suggestion importance[1-10]: 8 Why: The suggestion addresses a potential NullReferenceException by adding a null check for the capabilityName parameter, which is important for runtime stability and follows C# nullable reference type best practices.	8
	Add null check for proxy Add null check for proxyCapability before accessing it to prevent potential NullReferenceException in GenerateDesiredCapabilities. dotnet/src/webdriver/DriverOptions.cs [540-544] -Dictionary<string, object?>? proxyCapability = this.Proxy.ToCapability(); +Dictionary<string, object?>? proxyCapability = this.Proxy?.ToCapability(); if (!isSpecificationCompliant) { - proxyCapability = this.Proxy.ToLegacyCapability(); + proxyCapability = this.Proxy?.ToLegacyCapability(); } Apply this suggestion Suggestion importance[1-10]: 8 Why: The suggestion prevents potential NullReferenceException by adding null-conditional operators when accessing Proxy methods, which is crucial for runtime safety in a property that's already marked as nullable.	8

[nvborisenko]

In general I would say everything might be nullable. But changing bool to bool? is a breaking change? Is it transformed from bool to Nullable<bool>? If yes, then proceed as is without breaking changes.

[RenderMichael]

It is a breaking change, users would be affected if they read the property. All the reference types are made nullable here.