docs: private Map<URI, URI> addFilePrefix(final Map<URI, URI> set) {
          final Map<URI, URI> newSet = new HashMap<>();
          for (final Map.Entry<URI, URI> file: set.entrySet()) {
              final URI key = tempFileNameScheme.generateTempFileName(file.getKey());
              final URI value = tempFileNameScheme.generateTempFileName(file.getValue());
              newSet.put(key, value);
          }
          return newSet;
      }