[dotnet] Annotate nullability on firefox and chromium options

[RenderMichael]

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Annotate nullability on firefox and chromium options

Motivation and Context

Contributes to #14640

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.

[qodo-code-review]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

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

🧪 No relevant tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Null Handling The SetEnvironmentVariable method accepts a nullable string parameter but doesn't validate if variableValue is null before using it. While it's handled by setting empty string, this should be documented in the method's XML comments. public void SetEnvironmentVariable(string variableName, string? variableValue) { if (string.IsNullOrEmpty(variableName)) { throw new ArgumentException("Environment variable name cannot be null or an empty string"); } this.environmentVariables[variableName] = variableValue ?? string.Empty; }

[qodo-code-review]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Score
Possible issue	Validate individual arguments for null/empty The AddArguments() method with params string[] parameter should validate individual arguments, not just check if the array is null. Each argument should be validated to not be null or empty. dotnet/src/webdriver/Firefox/FirefoxOptions.cs [150-153] public void AddArguments(params string[] argumentsToAdd) { + if (argumentsToAdd == null) + throw new ArgumentNullException(nameof(argumentsToAdd)); + + foreach(var arg in argumentsToAdd) + { + if (string.IsNullOrEmpty(arg)) + throw new ArgumentException("Arguments cannot be null or empty", nameof(argumentsToAdd)); + } this.AddArguments((IEnumerable<string>)argumentsToAdd); } Apply this suggestion Suggestion importance[1-10]: 8 Why: The suggestion addresses a potential bug where invalid (null/empty) arguments could be silently accepted. Adding validation for individual arguments improves robustness and helps catch errors earlier.	8