Space as preprocessing param is considered invalid input for XML import

Consider the following scenario:

1. Create a template.
2. Create an item.
3. Add a preprocessing step "Trim" with a single space as a param.
4. Export the template.
5. Try to import the template, and the result is:
   

   Incorrect value for field "params": cannot be empty. [conf.import.php:162 ? CApiWrapper->__call() ? CFrontendApiWrapper->callMethod() ? CApiWrapper->callMethod() ? CFrontendApiWrapper->callClientMethod() ? CLocalApiClient->callMethod() ? CConfiguration->import() ? CConfigurationImport->import() ? CConfigurationImport->processItems() ? CItem->update() ? CItemGeneral->checkInput() ? CItem->checkSpecificFields() ? CItemGeneral->validateItemPreprocessing() ? CApiService::exception() in include/classes/api/services/CItemGeneral.php:953]