@Override
  public boolean verify(StatisticsFactory factory) {
    return (super.verify(factory) && (-1 != functorId));
  }
Implementation of {@link StatAlertDefinition}, which defines function Function to be applied on
all the statistic Threshold is valid for value evaluated by function
geode-core/src/main/java/org/apache/geode/internal/admin/statalerts/FunctionDecoratorImpl.java