message: Extract appendQueryParams in its own method
diff: @@ -182,12 +182,7 @@ export default class JSONAPISource extends Source implements Pullable, Pushable,
  fetch(url: string, customSettings?: FetchSettings): Promise<any> {
  let settings = this.initFetchSettings(customSettings);
  -
  - let fullUrl = url;
  - if (settings.params) {
  - fullUrl = appendQueryParams(fullUrl, settings.params);
  - delete settings.params;
  - }
  + let fullUrl = this.appendQueryParams(url, settings);
  let fetchFn = (Orbit as any).fetch || Orbit.globals.fetch;
  @@ -245,6 +240,15 @@ export default class JSONAPISource extends Source implements Pullable, Pushable,
  return settings;
  }
  + protected appendQueryParams(url: string, settings: FetchSettings): string {
  + let fullUrl = url;
  + if (settings.params) {
  + fullUrl = appendQueryParams(fullUrl, settings.params);
  + delete settings.params;
  + }
  + return fullUrl;
  + }
  +
  protected async handleFetchResponse(response: Response): Promise<any> {
  if (response.status === 201) {
  if (this.responseHasContent(response)) {
  