docs: public static Path getWindupRulesDir()
      {
          String rulesDir = System.getProperty(WINDUP_RULESETS_DIR_SYSPROP);
          if (rulesDir != null)
          {
              Path path = Paths.get(rulesDir);
              if (!path.toFile().exists())
                  LOG.warning(WINDUP_RULESETS_DIR_SYSPROP + " points to a non-existent directory!" + path.toAbsolutePath().toString());
              return path;
          }
          else
              return getWindupSubdirectory(RULES_DIRECTORY_NAME);
      }