question: private DateTimeZone generateTimeZone ( String timeZoneId , DateTimeZone systemTimeZone ) { if ( timeZoneId == null ) { return systemTimeZone ; } try { return DateTimeZone . forID ( timeZoneId ) ; } catch ( IllegalArgumentException ignored ) { LOG . debug ( INVALID_TIME_ZONE . logFormat ( timeZoneId ) ) ; throw new BadApiRequestException ( INVALID_TIME_ZONE . format ( timeZoneId ) ) ; } }
target:  Get the timezone for the request.