question: @ Override protected boolean isBehaviorSource ( FacesContext ctx , String behaviorSourceId , String componentClientId ) { if ( behaviorSourceId == null ) { return false ; } char sepChar = UINamingContainer . getSeparatorChar ( ctx ) ; String actualBehaviorId ; if ( behaviorSourceId . lastIndexOf ( sepChar ) != - 1 ) { actualBehaviorId = behaviorSourceId . substring ( 0 , behaviorSourceId . lastIndexOf ( sepChar ) ) ; } else { actualBehaviorId = behaviorSourceId ; } return ( actualBehaviorId . equals ( componentClientId ) ) ; }
target:  We override isBehaviorSource since the ID of the activated check box will have been augmented with the option number.