code: private void initEventTypes(IoEventType... eventTypes) {
          if ((eventTypes == null) || (eventTypes.length == 0)) {
              eventTypes = DEFAULT_EVENT_SET;
          }
  
          // Copy the list of handled events in the event set
          this.eventTypes = EnumSet.of(eventTypes[0], eventTypes);
          
          // Check that we don't have the SESSION_CREATED event in the set
          if (this.eventTypes.contains( IoEventType.SESSION_CREATED )) {
              this.eventTypes = null;
              throw new IllegalArgumentException(IoEventType.SESSION_CREATED
                  + " is not allowed.");
          }
      }
docs: Create an EnumSet from an array of EventTypes, and set the associated
  eventTypes field.
  
  @param eventTypes The array of handled events