code: public User createAccountWithHashedPassword(String userName, String hashedPassword) throws IOException {
          if (!PASSWORD_ENCODER.isPasswordHashed(hashedPassword)) {
              throw new IllegalArgumentException("this method should only be called with a pre-hashed password");
          }
          User user = User.getById(userName, true);
          user.addProperty(Details.fromHashedPassword(hashedPassword));
          SecurityListener.fireUserCreated(user.getId());
          return user;
      }
docs: Creates a new user account by registering a JBCrypt Hashed password with the user.
  
  @param userName The user's name
  @param hashedPassword A hashed password, must begin with <code>#jbcrypt:</code>