code: public Traverson startWith(final String uri) {
          startWith = hrefToUrl(uri);
          contextUrl = startWith;
          lastResult = null;
          return this;
      }
docs: Start traversal at the application/hal+json resource idenfied by {@code uri}.
  
  @param uri the {@code URI} of the initial HAL resource.
  @return Traverson initialized with the {@link HalRepresentation} identified by {@code uri}.