default String[] getCrawlerDocumentSpaces() {
        String[] spaces = (String[]) propMap.get(CRAWLER_DOCUMENT_SPACES);
        if (spaces == null) {
            spaces = Arrays.stream(getCrawlerDocumentSpaceCharsAsArray()).mapToObj(Character::toString).toArray(n -> new String[n]);
            propMap.put(CRAWLER_DOCUMENT_SPACES, spaces);
        }
        return spaces;
    }

 *
 * Neither of the built-in URL models offer direct access to path segments or query parameters.
 * Manually using `StringBuilder` to assemble these components is cumbersome: do '+' characters get
 * silently replaced with spaces? If a query parameter contains a '&', does that get escaped?
 * By offering methods to read and write individual query parameters directly, application
 * developers are saved from the hassles of encoding and decoding.
 *

    HTTP/2 server, close all but the first connection.
 *  Fix: Fail the HTTP/2 connection if first frame isn't `SETTINGS`.
 *  Fix: Forbid spaces in header names.
 *  Fix: Don't offer to do gzip if the request is partial.
 *  Fix: MockWebServer is now usable with JUnit 5. That update [broke the rules][junit_5_rules].

     * value}
     */
    void setValue(S segment, E entry, V value);
  }

  /**
   * An entry in a hash table of a {@link Segment}.
   *
   * <p>Entries in the map can be in the following states:
   *
   * <p>Valid: - Live: valid key/value are set
   *
   * <p>Invalid: - Collected: key/value was partially collected, but not yet cleaned up
   */