code: public boolean shouldInvalidate (Object id, int sourceOfInvalidation, int causeOfInvalidation) {
      	boolean retVal = true;
          if (preInvalidationListenerCount > 0) {
          	// In external implementation, catch any exceptions and process
          	try {
          		retVal = currentPreInvalidationListener.shouldInvalidate(id, sourceOfInvalidation, causeOfInvalidation);
          	}
          	catch (Throwable t) {
          		com.ibm.ws.ffdc.FFDCFilter.processException(t, "com.ibm.ws.cache.DCEventSource.shouldInvalidate", "120", this);
          		if (tc.isDebugEnabled()) {
              		Tr.debug(tc, "Exception thrown in shouldInvalidate method of PreInvalidationListener\n" + t.toString());
              	}
          	}
          }
          
          return retVal; //invalidate
      }
docs: The listeners are called when the preInvalidate method is invoked.
  @param event The invalidation event to be pre-invalidated.