Report the desired message in an application specific format.

  Report the desired message in an application specific format.
Only warnings and non-fatal errors should be reported through
this interface.
Fatal errors should be thrown as XMLStreamException.
Parameters:
- message - the error message
- errorType - an implementation defined error type
- relatedInformation - information related to the error, if available
- location - the location of the error, if available
Throws:
- XMLStreamException -