code: private final int load_digits(StringBuilder sb, int c) throws IOException
      {
          if (!IonTokenConstsX.isDigit(c))
          {
              return c;
          }
          sb.append((char) c);
  
          return readNumeric(sb, Radix.DECIMAL, NumericState.DIGIT);
      }
docs: Accumulates digits into the buffer, starting with the given character.
  
  @return the first non-digit character on the input. Could be the given
  character if its not a digit.
  
  @see IonTokenConstsX#isDigit(int)