code: public static KeyManager[] initializeKeyManagers(File _keyStoreFile, String _keyStorePassword, String _keyPassword) throws IOException {
          if (_keyStoreFile == null) {
              return null;
          }
  
          String keyStorePwd = StringUtil.defaultIfBlank(_keyStorePassword, System.getProperty("javax.net.ssl.keyStorePassword"));
          if (StringUtil.isBlank(keyStorePwd)) {
              keyStorePwd = "changeit";
          }
  
          String keyPwd = StringUtil.defaultIfBlank(_keyPassword, System.getProperty("javax.net.ssl.keyStorePassword"));
          if (StringUtil.isBlank(keyPwd)) {
              keyPwd = "changeit";
          }
  
          String storeType = getStoreTypeByFileName(_keyStoreFile);
          LOGGER.debug("Creating key store of type '" + storeType + "' from file '" + _keyStoreFile + "'");
  
          try {
              KeyManagerFactory keyMgrFactory = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());
              KeyStore keyStore = KeyStore.getInstance(storeType);
  
              try (FileInputStream fis = new FileInputStream(_keyStoreFile)) {
                  keyStore.load(fis, keyStorePwd.toCharArray());
              }
  
              keyMgrFactory.init(keyStore, keyPwd.toCharArray());
              return keyMgrFactory.getKeyManagers();
  
          } catch (Exception _ex) {
              throw new IOException("Error while setting up keyStore", _ex);
          }
      }
docs: Initialization of keyStoreManager used to provide access to the configured keyStore.
  
  @param _keyStoreFile key store file
  @param _keyStorePassword key store password
  @param _keyPassword key password
  @return KeyManager array or null
  @throws IOException on error