// open the file
        fileName = "my_output.p12";
        OutputStream outFile = new FileOutputStream (fileName);

        // get privatekey and cert details ...
        // ...

        // initialize
        // note: I have also tried:  KeyStore.getInstance("PKCS12", "BC");
        KeyStore keyStore = KeyStore.getInstance("PKCS12");
        keyStore.load(null, null);

        // this line doesn't add my password "test_pass" !
        keyStore.setKeyEntry("test_alias", myExistingPrivateKey, "key_pass".toCharArray(), myExistingCertChain);


        // store keystore and close file
        keyStore.store(outFile, "container_pass".toCharArray());
        outFile.close();