Open APIのスキーマ定義からメソッドごとにパスを取得する型

type Paths = {
    '/items': {
        GET: unknown
        POST: unknown
    }
    '/items/:id': {
        GET: unknown
        PUT: unknown
        DELETE: unknown
    }
    '/others': {
        GET: unknown
    }
}

type Method = 'GET' | 'POST' | 'PUT' | 'DELETE'
type FilteredPathsBy<M extends Method> =  {
  [K in keyof Paths]: M extends keyof Paths[K] ? K : never
}[keyof Paths]

/**
 * HTTPメソッドごとにパスを取得する
 */
type GetPaths = FilteredPathsBy<'GET'>
//   ^? '/items' | '/items/:id' | '/others'
type PostPaths = FilteredPathsBy<'POST'>
//   ^? '/items'
type PutPaths = FilteredPathsBy<'PUT'>
//   ^? '/items/:id'
type DeletePaths = FilteredPathsBy<'DELETE'>
//   ^? '/items/:id'