code: protected String parseFNameForError()
          throws XMLStreamException
      {
          StringBuilder sb = new StringBuilder(100);
          while (true) {
              char c;
  
              if (mInputPtr < mInputEnd) {
                  c = mInputBuffer[mInputPtr++];
              } else { // can't error here, so let's accept EOF for now:
                  int i = getNext();
                  if (i < 0) {
                      break;
                  }
                  c = (char) i;
              }
              if (c != ':' && !isNameChar(c)) {
                  --mInputPtr;
                  break;
              }
              sb.append(c);
          }
          return sb.toString();
      }
docs: Method called to read in full name, including unlimited number of
  namespace separators (':'), for the purpose of displaying name in
  an error message. Won't do any further validations, and parsing
  is not optimized: main need is just to get more meaningful error
  messages.