code: @Override
  	public Certificate engineGetCertificate(String s) {
  		ResourceTrustAnchor trustAnchor = getCertificateEntry(s);
  		if (trustAnchor != null) {
  			try {
  				return trustAnchor.getTrustAnchor().getTrustedCert();
  			} catch (ResourceStoreException e) {
  				return null;
  			}
  		}
  		return null;
  	}
docs: Get the certificate referenced by the supplied alias.
  
  @param s
  The alias.
  @return The Certificate or null if the alias does not exist in the
  keyStore.