code: protected final char getNextCharFromCurrent(String errorMsg)
          throws XMLStreamException
      {
          if (mInputPtr >= mInputEnd) {
              loadMoreFromCurrent(errorMsg);
          }
          return mInputBuffer[mInputPtr++];
      }
docs: Similar to {@link #getNextChar}, but will not read more characters
  from parent input source(s) if the current input source doesn't
  have more content. This is often needed to prevent "runaway" content,
  such as comments that start in an entity but do not have matching
  close marker inside entity; XML specification specifically states
  such markup is not legal.