Annotation Interface OnIdleCheck
The annotated methods are invoked with one optional argument `ControllerIoState` to check the idleness of controllers.
 The lowest value of the longs returned by the methods is used as a delay in milliseconds after which the methods are invoked next time.
 If the lowest value is less than zero, the corresponding controllers are scheduled to be destroyed.
 
 @OnIdleCheck
 static long onIdleCheck( ControllerIo io ){
    if( io.getIdleTime() < 10000 ) {
       return 1000;   // Check 1 second later
    } else {
       return -1;     // Destroy this controller
    }
 }
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