You can create a filter so that it only publishes the drawings. I had the same requirement when i was at a customer years ago. I don't have the rest of the configuration that calls this class, i believe it's just one of the wvs.properties that sets the method that you would use to validate the data.
I think these are the properties in wvs.properties, and you would specify the class and method name. Try it in the first one, it's been years since i did this.
public class DrawingFilter
public static boolean isDrawing(EPMDocument epmdocument)
if (epmdocument != null && (epmdocument instanceof EPMDocument))