code: protected static CertificateFactory getCertificateFactory()
              throws GeneralSecurityException {
          if (provider == null) {
              return CertificateFactory.getInstance("X.509");
          } else {
              return CertificateFactory.getInstance("X.509", provider);
          }
      }
docs: Returns appropriate <code>CertificateFactory</code>. If <I>provider</I>
  was set a provider-specific <code>CertificateFactory</code> will be used.
  Otherwise, a default <code>CertificateFactory</code> will be used.
  
  @return <code>CertificateFactory</code>