reply headers types error

What is the expected behavior?

What is the actual behavior? Upgrading to nock 12.0.1 I get error with this header

const headers: IncomingHttpHeaders = { 'content-type': 'application/json' };
nock('basepath.com')
            .post(`/path`, '{"body": "data"}')
            .once()
            .reply(200, '{"responseBody": "data"}', headers);

Error:(183, 11) TS2769: No overload matches this call.
  Overload 1 of 5, '(statusCode: number, replyBodyFnWithCallback: (this: ReplyFnContext, uri: string, body: Body, callback: (err: ErrnoException | null, result: ReplyBody) => void) => void, headers?: Record<...> | ... 2 more ... | undefined): Scope', gave the following error.
    Argument of type 'string' is not assignable to parameter of type '(this: ReplyFnContext, uri: string, body: Body, callback: (err: ErrnoException | null, result: ReplyBody) => void) => void'.
  Overload 2 of 5, '(statusCode: number, replyBodyFn: (this: ReplyFnContext, uri: string, body: Body) => string | Buffer | Record<string, any> | ReadStream | Promise<...>, headers?: Record<...> | ... 2 more ... | undefined): Scope', gave the following error.
    Argument of type 'string' is not assignable to parameter of type '(this: ReplyFnContext, uri: string, body: Body) => string | Buffer | Record<string, any> | ReadStream | Promise<ReplyBody>'.
  Overload 3 of 5, '(responseCode?: number | undefined, body?: string | Record<string, any> | undefined, headers?: Record<string, ReplyHeaderValue> | Map<string, ReplyHeaderValue> | ReplyHeaderValue[] | undefined): Scope', gave the following error.
    Argument of type 'IncomingHttpHeaders' is not assignable to parameter of type 'Record<string, ReplyHeaderValue> | Map<string, ReplyHeaderValue> | ReplyHeaderValue[] | undefined'.
      **Type 'IncomingHttpHeaders' is not assignable to type 'ReplyHeaderValue[]'.**

Versions

Software	Version(s)
Nock	^12.0.1
Node	12.13.0
TypeScript	3.8.2

[mastermatt]

I’m assuming IncomingHttpHeaders is from the stdlib http in @types/node, correct?

[paulmelnikow]

Thanks @mastermatt, I appreciate the subtlety of your explanation.