Added nullable enums support

[m0a0k0s]

No description provided.

[Copilot]

Pull request overview

This PR adds support for nullable enum types in the Swashbuckle AspNetCore extensions by detecting and extracting the underlying enum type from nullable wrappers before processing.

Key Changes:

• Nullable enum type handling in schema and parameter filters using Nullable.GetUnderlyingType()
• Consistent use of the underlying enum type for generating enum names and descriptions
• Filtering of OpenApiNull elements when processing enum documentation to maintain alignment with extension arrays

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
XEnumNamesSchemaFilter.cs	Extracts underlying type from nullable enums and uses it consistently for enum name and description generation
XEnumNamesParameterFilter.cs	Adds nullable enum type detection for parameter filtering
EnumTypeExtensions.cs	Filters out null elements from schema.Enum collection to ensure proper alignment with extension arrays that contain only actual enum values

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.