[v4] Class within square brackets [] is ignored

[andrewrauber]

What version of Tailwind CSS are you using?

4.0.3

What build tool (or framework if it abstracts the build tool) are you using?

tailwind-cli

What version of Node.js are you using?

v22.13.1

What browser are you using?

N/A

What operating system are you using?

Windows

Describe your issue

I have a Blazor project where some classes are in c#.
This works fine and generates the correct output, except for a specific case where my classes are wrapped in square braces.
The following code doesn't generate the expected gap-y-4, gap-y-6, and gap-y-8 classes in the output.

public enum StackSpacing
{
    [CssClass("gap-y-4")]
    Small,
    [CssClass("gap-y-6")]
    Medium,
    [CssClass("gap-y-8")]
    Large
}

If I remove the square brackets, then the expected classes are generated in the output.
If I put a space between the opening bracket ( [ ) and CssClass, then also the expected classes are generated in the output.
If I change the word "CssClass" to be lowercase, then also the expected classes are generated in the output.