Cannot create and use custom icon sets with kubejs

[DontkillBelalus-scu]

Checked for existing issues

• I have checked for existing issues, and have found none.

Tested latest version

• I have checked that this occurs on the latest version.

GregTech CEu Version

v7.4.1

Minecraft Version

1.20.1 Forge

Recipe Viewer Installed

JEI

Environment

Singleplayer

Cross-Mod Interaction

Unsure

Other Installed Mods

• JEI
• GregTech Modern
• Create
• Rhino
• Modern UI
• Jade
• Architectury API
• Configuration
• KubeJS
• LDLib

Expected Behavior

Expected to add a material "magnetohydrodynamically_constrained_star_matter" that has the custom icon set CONSTRAINEDMAGMATTER.

Actual Behavior

KubeJS throws an error.

Steps to Reproduce

GTCEuStartupEvents.registry('gtceu:material_icon_set', e => {

    e.create('constrainedmagmatter')

})

GTCEuStartupEvents.registry('gtceu:material', e => {

    e.create("magnetohydrodynamicallyconstrainedstarmatter")
         .color(0xffffff)
         .secondaryColor(0xffffff)
         .ingot()
         .element(GTElements.get("raw_star_matter"))
         .iconSet(GTMaterialIconSet.CONSTRAINEDMAGMATTER)
         .flags(GTMaterialFlags.GENERATE_PLATE)
         
})

I tried to add .parent('dull'), but that doesn't work.

Additional Information

Likely this method is out-of-date.

[DontkillBelalus-scu]

Ignore that in Steps to Reproduce, the material name "magnetohydrodynamicallyconstrainedstarmatter" didn't have the underscore.
But it's the same no matter if you add the underscore.

[DontkillBelalus-scu]

Actually, I was wrong.
Change .iconSet(GTMaterialIconSet.CONSTRAINEDMAGMATTER) into .iconSet('constrainedmagmatter') and it's solved.