WsdlToPhp\PackageGenerator\Model\Struct::addValue PHP Method

    public function addValue($value)
    {
        if ($this->getValue($value) === null) {
            $this->values->add(new StructValue($this->getGenerator(), $value, $this->getValues()->count(), $this));
            $this->setIsRestriction(true);
            $this->setIsStruct(true);
        }
        return $this;
    }