docs: private static boolean looksUnsafeForFastParser(String s) {
          boolean lastWasDot = true; // start of path is also a "dot"
          int len = s.length();
          if (s.isEmpty())
              return true;
          if (s.charAt(0) == '.')
              return true;
          if (s.charAt(len - 1) == '.')
              return true;
  
          for (int i = 0; i < len; ++i) {
              char c = s.charAt(i);
              if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || c == '_') {
                  lastWasDot = false;
                  continue;
              } else if (c == '.') {
                  if (lastWasDot)
                      return true; // ".." means we need to throw an error
                  lastWasDot = true;
              } else if (c == '-') {
                  if (lastWasDot)
                      return true;
                  continue;
              } else {
                  return true;
              }
          }
  
          if (lastWasDot)
              return true;
  
          return false;
      }