message: refactor(aio): move document path computation
  Do the path computation before doing the cache look up.
diff: @@ -29,14 +29,14 @@ export class DocumentService {
  private getDocument(url: string) {
  this.logger.log('getting document', url);
  - if ( !this.cache.has(url)) {
  - this.cache.set(url, this.fetchDocument(url));
  + const path = this.computePath(url);
  + if ( !this.cache.has(path)) {
  + this.cache.set(path, this.fetchDocument(path));
  }
  - return this.cache.get(url);
  + return this.cache.get(path);
  }
  - private fetchDocument(url: string) {
  - const path = this.computePath(url);
  + private fetchDocument(path: string) {
  this.logger.log('fetching document from', path);
  const subject = new AsyncSubject();
  this.http
  