feat: Enable null reference types

[pm7y]

No description provided.

[Copilot]

Pull request overview

This PR enables nullable reference types across the entire codebase, a significant modernization effort that improves type safety and eliminates many potential null reference errors. The changes include:

• Enabled nullable reference types (<Nullable>enable</Nullable>) and treat warnings as errors
• Added Meziantou.Analyzer for enhanced code quality checks
• Converted mutable properties to init-only and added required modifiers where appropriate
• Updated all nullable annotations throughout the codebase
• Converted several classes to record types for immutability
• Added proper StringComparison parameters to string operations
• Updated error messages to be more descriptive and schema-specific
• Enhanced validation and null-safety throughout

Reviewed changes

Copilot reviewed 97 out of 97 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
Directory.Build.props	Enabled nullable reference types and warnings as errors, added Meziantou.Analyzer
Directory.Packages.props	Added Meziantou.Analyzer package reference
Settings classes	Converted properties to init-only with required modifiers and nullable annotations
EventGridEvent/CloudEvent	Added required modifiers, improved validation messages
Middleware classes	Enhanced error handling with detailed error codes and null-safe operations
Service classes	Added nullable annotations and proper null checks
Record types	Converted DTOs to records for immutability
Test files	Updated to use required properties and null-aware assertions
.editorconfig	Added Meziantou.Analyzer rule configurations

The changes are comprehensive and well-executed, successfully modernizing the codebase to use nullable reference types throughout.

[Copilot]

Pull request overview

Copilot reviewed 100 out of 100 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (5)

src/AzureEventGridSimulator/Infrastructure/Middleware/EventGridMiddleware.cs:1

• The code performs a case-insensitive check using StringComparison.OrdinalIgnoreCase, but then uses String.Replace with the same comparison. Consider using StringComparison.Ordinal for the StartsWith check since the constant should match exactly, or document why case-insensitive comparison is needed for authorization headers.
  src/AzureEventGridSimulator/Infrastructure/Settings/Subscribers/SubscribersSettings.cs:1
• The properties are now nullable with set accessors, but previously had default empty array initializers. The computed properties like All handle null correctly, but this creates inconsistency. Consider using init instead of set for consistency with other settings classes, or restore the empty array defaults to maintain backward compatibility with code that may not expect null values.
  src/AzureEventGridSimulator/Infrastructure/Settings/Subscribers/SubscribersSettings.cs:1
• The properties are now nullable with set accessors, but previously had default empty array initializers. The computed properties like All handle null correctly, but this creates inconsistency. Consider using init instead of set for consistency with other settings classes, or restore the empty array defaults to maintain backward compatibility with code that may not expect null values.
  src/AzureEventGridSimulator/Infrastructure/Settings/Subscribers/SubscribersSettings.cs:1
• The properties are now nullable with set accessors, but previously had default empty array initializers. The computed properties like All handle null correctly, but this creates inconsistency. Consider using init instead of set for consistency with other settings classes, or restore the empty array defaults to maintain backward compatibility with code that may not expect null values.
  src/AzureEventGridSimulator/Infrastructure/Settings/Subscribers/SubscribersSettings.cs:1
• The properties are now nullable with set accessors, but previously had default empty array initializers. The computed properties like All handle null correctly, but this creates inconsistency. Consider using init instead of set for consistency with other settings classes, or restore the empty array defaults to maintain backward compatibility with code that may not expect null values.

[Copilot]

The test name 'GivenDefaultSettings_ThenAllArraysAreNull' uses 'Arrays' but these are properties that hold array references. Consider renaming to 'GivenDefaultSettings_ThenAllSubscriberPropertiesAreNull' for clarity.

Suggested change

	public void GivenDefaultSettings_ThenAllArraysAreNull()
	public void GivenDefaultSettings_ThenAllSubscriberPropertiesAreNull()

[Copilot]

The test name 'GivenDefaultSettings_ThenAllArraysAreNull' uses 'Arrays' but these are properties that hold array references. Consider renaming to 'GivenDefaultSettings_ThenAllSubscriberPropertiesAreNull' for clarity.