// Retrieve information about the window being accessed.
if( walker.getClass().isAnnotationPresent(Reference.class) ) {
Window window = walker.getClass().getAnnotation(Reference.class).window();
if( window.start() > 0 ) throw new ReviewedGATKException( "Reference window starts after current locus" );
if( window.stop() < 0 ) throw new ReviewedGATKException( "Reference window ends before current locus" );
windowStart = window.start();
windowStop = window.stop();
}
else {