code: public static StorageUri appendPathToUri(final StorageUri uriList, final String relativeOrAbsoluteUri,
              final String separator) throws URISyntaxException {
          return new StorageUri(appendPathToSingleUri(uriList.getPrimaryUri(), relativeOrAbsoluteUri, separator),
                  appendPathToSingleUri(uriList.getSecondaryUri(), relativeOrAbsoluteUri, separator));
      }
docs: Appends a path to a list of URIs correctly using "/" as separator.
  
  @param uriList
  The base Uri.
  @param relativeOrAbslouteUri
  The relative or absloute URI.
  @return The appended Uri.
  @throws URISyntaxException