code: public KeePassFile openDatabase(File keyFile) {
          if (keyFile == null) {
              throw new IllegalArgumentException("You must provide a valid KeePass keyfile.");
          }
  
          try {
              return openDatabase(new FileInputStream(keyFile));
          } catch (FileNotFoundException e) {
              throw new IllegalArgumentException("The KeePass keyfile could not be found. You must provide a valid KeePass keyfile.", e);
          }
      }
docs: Opens a KeePass database with the given keyfile and returns the
  KeePassFile for further processing.
  <p>
  If the database cannot be decrypted with the provided password an
  exception will be thrown.
  
  @param keyFile
  the password to open the database
  @return a KeePassFile the keyfile to open the database
  @see KeePassFile