This is a modified version of built-in Partial<:

/**
 * Mark all properties as maybe undefined (`T | undefined`)
 *
 * With `Partial`, properties can be omitted, they are optional.
 * With `MaybeUndefined` all properties are required, but may be explicitly set to `undefined`.
 *
 * This is most useful if `compilerOptions.exactOptionalPropertyTypes` is set to `true`.
 * This option was introduced in TS v4.4:
 *   https://www.typescriptlang.org/tsconfig#exactOptionalPropertyTypes
 */
type MaybeUndefined<T> = {
  [P in keyof T]: T[P] | undefined
}

Here's the built-in/native Partial:

/**
 * Make all properties in T optional
 */
type Partial<T> = {
    [P in keyof T]?: T[P];
};