code: @Override
      public boolean isEligibleFor(Object criterion) {
          return criterion.equals(Event.class) || criterion.equals(kind);
      }
docs: Returns `true` if the criterion is `Event.class` (representing
  "any event") or if the criterion is a String equal to this
  event's kind (the String passed to the constructor).
  
  @see org.jgrapes.core.Eligible#isEligibleFor(java.lang.Object)