Neos\Neos\Service\Mapping\NodePropertyConverterService::convertValue PHP Method

    protected function convertValue($propertyValue, $dataType)
    {
        $rawType = TypeHandling::truncateElementType($dataType);
        // This hardcoded handling is to circumvent rewriting PropertyMappers that convert objects. Usually they expect the source to be an object already and break if not.
        if (!TypeHandling::isSimpleType($rawType) && !is_object($propertyValue) && !is_array($propertyValue)) {
            return null;
        }
        if ($rawType === 'array') {
            $conversionTargetType = 'array<string>';
        } elseif (TypeHandling::isSimpleType($rawType)) {
            $conversionTargetType = TypeHandling::normalizeType($rawType);
        } else {
            $conversionTargetType = 'array';
        }
        $propertyMappingConfiguration = $this->createConfiguration($dataType);
        $convertedValue = $this->propertyMapper->convert($propertyValue, $conversionTargetType, $propertyMappingConfiguration);
        if ($convertedValue instanceof \Neos\Error\Messages\Error) {
            throw new PropertyException($convertedValue->getMessage(), $convertedValue->getCode());
        }
        return $convertedValue;
    }