code: @Deprecated
      protected static KeyManagerFactory buildKeyManagerFactory(File certChainFile,
              String keyAlgorithm, File keyFile, String keyPassword, KeyManagerFactory kmf)
                      throws KeyStoreException, NoSuchAlgorithmException, NoSuchPaddingException,
                      InvalidKeySpecException, InvalidAlgorithmParameterException, IOException,
                      CertificateException, KeyException, UnrecoverableKeyException {
          return buildKeyManagerFactory(toX509Certificates(certChainFile), keyAlgorithm,
                                        toPrivateKey(keyFile, keyPassword), keyPassword, kmf);
      }
docs: Build a {@link KeyManagerFactory} based upon a key algorithm, key file, key file password,
  and a certificate chain.
  @param certChainFile a X.509 certificate chain file in PEM format
  @param keyAlgorithm the standard name of the requested algorithm. See the Java Secure Socket Extension
  Reference Guide for information about standard algorithm names.
  @param keyFile a PKCS#8 private key file in PEM format
  @param keyPassword the password of the {@code keyFile}.
  {@code null} if it's not password-protected.
  @param kmf The existing {@link KeyManagerFactory} that will be used if not {@code null}
  @return A {@link KeyManagerFactory} based upon a key algorithm, key file, key file password,
  and a certificate chain.
  @deprecated will be removed.