code: private static boolean isV0Separator(final char c) {
          if (c < 0x20 || c >= 0x7f) {
              if (c != 0x09) {
                  throw UndertowMessages.MESSAGES.invalidControlCharacter(Integer.toString(c));
              }
          }
  
          return V0_SEPARATOR_FLAGS[c];
      }
docs: Returns true if the byte is a separator as defined by V0 of the cookie
  spec.