Missing isMaskOutline property in FigmaPlugin API

In Figma API there exists isMaskOutline property on Frame like objects

https://www.figma.com/developers/api#node-types

isMaskOutlineBoolean default: false
Does this mask ignore fill style (like gradients) and effects?

But am missing this data in Figma Plugin API:

Can found only isMask but isMaskOutline seems to be missing.
Is my observation correct, or is this field renamed or accessible in some different way?

Thank you for response
Jan