Neos\Media\TypeConverter\AssetInterfaceConverter::getTargetTypeForSource PHP Method

    public function getTargetTypeForSource($source, $originalTargetType, PropertyMappingConfigurationInterface $configuration = null)
    {
        $targetType = $originalTargetType;
        if (is_array($source) && array_key_exists('__type', $source)) {
            $targetType = $source['__type'];
            if ($configuration === null) {
                throw new \InvalidArgumentException('A property mapping configuration must be given, not NULL.', 1421443628);
            }
            if ($configuration->getConfigurationValue(ObjectConverter::class, self::CONFIGURATION_OVERRIDE_TARGET_TYPE_ALLOWED) !== true) {
                throw new InvalidPropertyMappingConfigurationException('Override of target type not allowed. To enable this, you need to set the PropertyMappingConfiguration Value "CONFIGURATION_OVERRIDE_TARGET_TYPE_ALLOWED" to TRUE.', 1421443641);
            }
            if ($targetType !== $originalTargetType && is_a($targetType, $originalTargetType, true) === false) {
                throw new InvalidDataTypeException('The given type "' . $targetType . '" is not a subtype of "' . $originalTargetType . '".', 1421443648);
            }
        }
        return $targetType;
    }