code: public void error( Marker marker, String msg, Throwable t )
      {
          if( m_delegate.isErrorEnabled() )
          {
              setMDCMarker( marker );
              m_delegate.error( msg, t );
              resetMDCMarker();
          }
      }
docs: This method is similar to {@link #error(String, Throwable)}
  method except that the marker data is also taken into
  consideration.
  
  @param marker the marker data specific to this log statement
  @param msg    the message accompanying the exception
  @param t      the exception (throwable) to log