Return the column number where the current document event ends.
Warning: The return value from the method
is intended only as an approximation for the sake of error
reporting; it is not intended to provide sufficient information
to edit the character content of the original XML document.
The return value is an approximation of the column number
in the document entity or external parsed entity where the
markup triggering the event appears.
return (null == m_locator) ? super.getColumnNumber() : m_locator.getColumnNumber();