src/Service/UserService.php
public function changePassword($data)
    {
        /* @var $user UserInterface */
        if (!($user = $this->hydrate($data, $this->getChangePasswordForm()))) {
            return;
        }

        $eventManager = $this->getEventManager();
        $eventManager->trigger(__METHOD__, $this, $user);

        $password = $user->getPassword();
        $passwordService = $this->getMapper()->getPasswordService();
        $user->setPassword($passwordService->create($password));
        $this->getMapper()->update($user)->save();

        $eventManager->trigger(__METHOD__ . '.post', $this, $user);

        return $user;
    }
public function changePassword($data)
    {
        /* @var $user UserInterface */
        if (!($user = $this->hydrate($data, $this->getChangePasswordForm()))) {
            return;
        }

        $eventManager = $this->getEventManager();
        $eventManager->trigger(__METHOD__, $this, $user);

        $password = $user->getPassword();
        $passwordService = $this->getMapper()->getPasswordService();
        $user->setPassword($passwordService->create($password));
        $this->getMapper()->update($user)->save();

        $eventManager->trigger(__METHOD__ . '.post', $this, $user);

        return $user;
    }
Change user password

@param array|UserInterface $data
@return UserInterface|void