Create and save a value object in CommandController - typo3

Question

im trying to create and save a value object in my ImportCommandController.php, but only the entity will be saved.
Let me show some code:
// Create Entity "Fewo"
$fewo = new Fewo();
$fewo->setTitle('MyFewo');
...
// Create Value Object "Period"
$period = new Period();
$period->setTitle('MyTestTitle');
...
$fewo->addPeriod($period);
$this->fewoRepository->add($fewo);
$this->persistenceManager->persistAll();
Now the Fewo is in the database, but the period-table is still empty. I can't find my mistake...
UPDATE:
This is the Period Model:
<?php
namespace TYPO3\Fewo\Domain\Model;
class Period extends \TYPO3\CMS\Extbase\DomainObject\AbstractValueObject {
/**
* Name der Saison
*
* #var \string
*/
protected $name;
/**
* Von
*
* #var \DateTime
*/
protected $begin;
/**
* Bis
*
* #var \DateTime
*/
protected $end;
/**
* rentalcharges
*
* #var \TYPO3\CMS\Extbase\Persistence\ObjectStorage<\TYPO3\Fewo\Domain\Model\Rentalcharge>
*/
protected $rentalcharges;
/**
* __construct
*
* #return Period
*/
public function __construct() {
//Do not remove the next line: It would break the functionality
$this->initStorageObjects();
}
/**
* Initializes all ObjectStorage properties.
*
* #return void
*/
protected function initStorageObjects() {
/**
* Do not modify this method!
* It will be rewritten on each save in the extension builder
* You may modify the constructor of this class instead
*/
$this->rentalcharges = new \TYPO3\CMS\Extbase\Persistence\ObjectStorage();
}
/**
* Returns the name
*
* #return \string $name
*/
public function getName() {
return $this->name;
}
/**
* Sets the name
*
* #param \string $name
* #return void
*/
public function setName($name) {
$this->name = $name;
}
/**
* Returns the begin
*
* #return \DateTime $begin
*/
public function getBegin() {
return $this->begin;
}
/**
* Sets the begin
*
* #param \DateTime $begin
* #return void
*/
public function setBegin($begin) {
$this->begin = $begin;
}
/**
* Returns the end
*
* #return \DateTime $end
*/
public function getEnd() {
return $this->end;
}
/**
* Sets the end
*
* #param \DateTime $end
* #return void
*/
public function setEnd($end) {
$this->end = $end;
}
/**
* Adds a Rentalcharge
*
* #param \TYPO3\Fewo\Domain\Model\Rentalcharge $rentalcharge
* #return void
*/
public function addRentalcharge(\TYPO3\Fewo\Domain\Model\Rentalcharge $rentalcharge) {
$this->rentalcharges->attach($rentalcharge);
}
/**
* Removes a Rentalcharge
*
* #param \TYPO3\Fewo\Domain\Model\Rentalcharge $rentalchargeToRemove The Rentalcharge to be removed
* #return void
*/
public function removeRentalcharge(\TYPO3\Fewo\Domain\Model\Rentalcharge $rentalchargeToRemove) {
$this->rentalcharges->detach($rentalchargeToRemove);
}
/**
* Returns the rentalcharges
*
* #return \TYPO3\CMS\Extbase\Persistence\ObjectStorage<\TYPO3\Fewo\Domain\Model\Rentalcharge> $rentalcharges
*/
public function getRentalcharges() {
return $this->rentalcharges;
}
/**
* Sets the rentalcharges
*
* #param \TYPO3\CMS\Extbase\Persistence\ObjectStorage<\TYPO3\Fewo\Domain\Model\Rentalcharge> $rentalcharges
* #return void
*/
public function setRentalcharges(\TYPO3\CMS\Extbase\Persistence\ObjectStorage $rentalcharges) {
$this->rentalcharges = $rentalcharges;
}
}
UPDATE2:
Tried:
class Period extends \TYPO3\CMS\Extbase\DomainObject\AbstractEntity {...}
and:
$period = $this->objectManager->get('TYPO3\Fewo\Domain\Model\Period');
with no effect :(

Answer 1

Is Period in FeWo of the right type?
It have to be something like this:
* #var \TYPO3\CMS\Extbase\Persistence\ObjectStorage<\TYPO3\Fewo\Domain\Model\Fewo>