question: public boolean isValidOn ( final Date date ) { if ( ( x509Certificate == null ) || ( date == null ) ) { return false ; } try { x509Certificate . checkValidity ( date ) ; return true ; } catch ( CertificateExpiredException e ) { return false ; } catch ( CertificateNotYetValidException e ) { return false ; } }
target:  Checks if the given date is in the validity period of the certificate.