message: docs: change ActivatedRouteStub code sample to work with strictNullChecks on
  convertToParamMap() does not accept undefined.
  Fix code sample so it can be used in strict mode without requiring changes.
  PR Close
diff: @@ -21,8 +21,8 @@ export class ActivatedRouteStub {
  /** The mock paramMap observable */
  readonly paramMap = this.subject.asObservable();
  - /** Set the paramMap observables's next value */
  - setParamMap(params?: Params) {
  + /** Set the paramMap observable's next value */
  + setParamMap(params: Params = {}) {
  this.subject.next(convertToParamMap(params));
  }
  }
  