code: public static void addPrivateKey(KeyStore keyStore, File pemKeyFile, char[] passwordChars, List<Certificate> certChain) throws IOException, GeneralSecurityException {
          final String methodName = "addPrivateKey";
          logger.entry(methodName, pemKeyFile, certChain);
  
          PrivateKey privateKey = createPrivateKey(pemKeyFile, passwordChars);
  
          keyStore.setKeyEntry("key", privateKey, passwordChars, certChain.toArray(new Certificate[certChain.size()]));
  
          logger.exit(methodName);
      }
docs: Adds a private key to the specified key store from the passed private key file and certificate chain.
  
  @param keyStore
  The key store to receive the private key.
  @param pemKeyFile
  A PEM format file containing the private key.
  @param passwordChars
  The password that protects the private key.
  @param certChain The certificate chain to associate with the private key.
  @throws IOException if the key store file cannot be read
  @throws GeneralSecurityException if a cryptography problem is encountered.