code: public static WildcardPattern create(String pattern, String directorySeparator) {
      String key = pattern + directorySeparator;
      return CACHE.computeIfAbsent(key, k -> new WildcardPattern(pattern, directorySeparator));
    }
docs: Creates pattern with specified separator for directories.
  <p>
  This is used to match Java-classes, i.e. <code>org.foo.Bar</code> against <code>org/**</code>.
  <b>However usage of character other than "/" as a directory separator is misleading and should be avoided,
  so method {@link #create(String)} is preferred over this one.</b>
  
  <p>
  Also note that no matter whether forward or backward slashes were used in the <code>antPattern</code>
  the returned pattern will use <code>directorySeparator</code>.
  Thus to match Windows-style path "dir\file.ext" against pattern "dir/file.ext" normalization should be performed.