question: private void registerDefaultValidatorIds ( Application application , LinkedHashSet < String > defaultValidatorIds ) { if ( defaultValidatorIds == null ) { defaultValidatorIds = new LinkedHashSet < > ( ) ; if ( isBeanValidatorAvailable ( ) ) { WebConfiguration webConfig = WebConfiguration . getInstance ( ) ; if ( ! webConfig . isOptionEnabled ( WebConfiguration . BooleanWebContextInitParameter . DisableDefaultBeanValidator ) ) { defaultValidatorIds . add ( BeanValidator . VALIDATOR_ID ) ; } } } for ( String validatorId : defaultValidatorIds ) { if ( LOGGER . isLoggable ( Level . FINE ) ) { LOGGER . log ( Level . FINE , MessageFormat . format ( "Calling Application.addDefaultValidatorId({0})" , validatorId ) ) ; } application . addDefaultValidatorId ( validatorId ) ; } }
target:  If defaultValidatorIds is null, then no &lt;default-validators&gt; element appeared in any configuration file. In that case, add javax.faces.Bean if Bean Validation is available. If the &lt;default-validators&gt; appeared at least once, don't add the default (and empty &lt;default-validator&gt; element disabled default validators)