How to add custom property key to useTheme()

[danhddao1997]

Hello, I would like to ask a question

In mapping.json file, I set a property text-heading-1-line-height like below:

{
  "strict": {
    "text-heading-1-font-size": 36,
    "text-heading-1-line-height": 54,

    ...
  }
  ...
}

But when I use useTheme()['text-heading-1-line-height'], it returns undefined

Where should I set up so that it returns 54?