docs: public static PrivateKeyEntry getFirstPrivateKeyEntryFromP12InputStream(final InputStream p12InputStream, final String password) throws KeyStoreException, IOException {
          Objects.requireNonNull(password, "Password may be blank, but must not be null.");
  
          final KeyStore keyStore = KeyStore.getInstance("PKCS12");
  
          try {
              keyStore.load(p12InputStream, password.toCharArray());
          } catch (NoSuchAlgorithmException | CertificateException e) {
              throw new KeyStoreException(e);
          }
  
          final Enumeration<String> aliases = keyStore.aliases();
          final KeyStore.PasswordProtection passwordProtection = new KeyStore.PasswordProtection(password.toCharArray());
  
          while (aliases.hasMoreElements()) {
              final String alias = aliases.nextElement();
  
              KeyStore.Entry entry;
  
              try {
                  try {
                      entry = keyStore.getEntry(alias, passwordProtection);
                  } catch (final UnsupportedOperationException e) {
                      entry = keyStore.getEntry(alias, null);
                  }
              } catch (final UnrecoverableEntryException | NoSuchAlgorithmException e) {
                  throw new KeyStoreException(e);
              }
  
              if (entry instanceof KeyStore.PrivateKeyEntry) {
                  return (PrivateKeyEntry) entry;
              }
          }
  
          throw new KeyStoreException("Key store did not contain any private key entries.");
      }