TYPO3 Flow Base Distribution

having a value object:
/** * A Price Value * * @Flow\ValueObject
*/
class Price{

/**
 * @var float
 * @FLOW\Validate(type="NotEmpty")
 * @ORM\Column(nullable=true,type="decimal",scale=2)
     */
    protected $value;

/**
 * @param float $value
     */
    public function __construct($value) {
        $this->value = $value;
    }

/**
 * @return float
     */
    public function getValue() {
        return $this->value;
    }
}

anything works fine until this:
in a doctrine collection wich contains prices, the type of property $value is "string" and not of type "double".
so the following fails: if($this->prices->contains($newPriceWithSameValue)) because property $value of "newPriceWithSameValue" is type of "double".