*/
public Object putSheetOverlay(String sheetName, String beanPath, Object value) {
Sheet sheet = getOrCreateSheet(sheetName);
Object prevVal = sheet.getMap().put(beanPath, value);
try {
sheet.prime();
} catch (TypeMismatchException tme) {
// revert to presumably non-damaging value
sheet.getMap().put(beanPath, prevVal);
throw tme;
}