code: @Override
  	public Certificate[] engineGetCertificateChain(String s) {
  		CredentialWrapper credential = getKeyEntry(s);
  		X509Certificate[] chain = new X509Certificate[0];
  		if (credential != null) {
  			try {
  				chain = credential.getCredential().getCertificateChain();
  			} catch (ResourceStoreException e) {
  				logger.warn(e.getMessage(), e);
  				chain = null;
  			}
  		}
  		return chain;
  	}
docs: Get the certificateChain for the key referenced by the alias.
  
  @param s
  The key alias.
  @return The key's certificate chain or a 0 length array if the key is not
  in the keystore.