code: private int getRealIndex(String qName) {
      int index = attributes.getIndex(qName);
      if (index < 0 || reverseIndex(index) < 0)
        return -1;
      return index;
    }
docs: Get the real index, in the initial attributes list of a given attribute.
  If the attribute is filtered out then return -1.
  @param qName The attribute qualified name.
  @return The real index if the attribute is present and not filtered out, otherwise -1.