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].

    // six-per-em space
    assertThat(parse("http://h/\u2006").encodedPath).isEqualTo("/%E2%80%86")
    // figure space
    assertThat(parse("http://h/\u2007").encodedPath).isEqualTo("/%E2%80%87")
    // punctuation space
    assertThat(parse("http://h/\u2008").encodedPath).isEqualTo("/%E2%80%88")
    // thin space
    assertThat(parse("http://h/\u2009").encodedPath).isEqualTo("/%E2%80%89")
    // hair space

  integrity sha512-XnAIvQ8eM+kC6aULx6wuQiwVsnzsi9d3WxzV3FpWTGA19F621kwdbsAcFKXgKUHZWsy+mY6iL1sHTxWEFCytDA==
  dependencies:
    balanced-match "^1.0.0"

braces@^3.0.2, braces@~3.0.2:
  version "3.0.2"
  resolved "https://registry.yarnpkg.com/braces/-/braces-3.0.2.tgz#3454e1a462ee8d599e236df336cd9ea4f8afe107"
  integrity sha512-b8um+L1RzM3WDSzvhm6gIz1yfTbBt6YTlcEKAvsmqCZZFw46z626lVj9j1yEPW33H5H+lBQpZMP1k8l+78Ha0A==
  dependencies:

 * which are <i>not the caller's fault</i>. Doing so is <b>not recommended</b> because it is
 * misleading to future readers of the code and of stack traces. See <a
 * href="https://github.com/google/guava/wiki/ConditionalFailuresExplained">Conditional failures
 * explained</a> in the Guava User Guide for more advice. Notably, {@link Verify} offers assertions

   * uniform, the actual concurrency observed may vary. Ideally, you should choose a value to
   * accommodate as many threads as will ever concurrently modify the table. Using a significantly
   * higher value than you need can waste space and time, and a significantly lower value can lead
   * to thread contention. But overestimates and underestimates within an order of magnitude do not

# Maximum size of symbol terms in documents.
crawler.document.max.symbol.term.size=10
# Whether to remove duplicate terms in documents.
crawler.document.duplicate.term.removed=false
# Unicode space characters for document parsing.
crawler.document.space.chars=u0009u000Au000Bu000Cu000Du001Cu001Du001Eu001Fu0020u00A0u1680u180Eu2000u2001u2002u2003u2004u2005u2006u2007u2008u2009u200Au200Bu200Cu202Fu205Fu3000uFEFFuFFFDu00B6

nt:"\f886"}.fa-sort-numeric-up:before{content:"\f163"}.fa-sort-numeric-up-alt:before{content:"\f887"}.fa-sort-up:before{content:"\f0de"}.fa-soundcloud:before{content:"\f1be"}.fa-sourcetree:before{content:"\f7d3"}.fa-spa:before{content:"\f5bb"}.fa-space-shuttle:before{content:"\f197"}.fa-speakap:before{content:"\f3f3"}.fa-speaker-deck:before{content:"\f83c"}.fa-spell-check:before{content:"\f891"}.fa-spider:before{content:"\f717"}.fa-spinner:before{content:"\f110"}.fa-splotch:before{content:"\f5bc...

  //
  // In the constructor of AbstractCatchingFuture, the delegate future is assigned to a field
  // 'inputFuture'. That field is non-final and non-volatile. There are 2 places where the
  // 'inputFuture' field is read and where we will have to consider visibility of the write
  // operation in the constructor.
  //