Field mapping not working properly

Problem/Motivation

During implementing a MediaType for https://www.drupal.org/project/riddle_marketplace, i discovered two problems in these if clause:

      if ($this->hasField($destination_field) && $this->{$destination_field}->isEmpty() && ($value = $this->getType()->getField($this, $source_field))) {
        $this->set($destination_field, $value);
      }

Riddle gives me a publishing status, so i wanted to map that to the media status field. First problem is, that it seems that base fields are never empty at this point. So it's not possible to map any base fields.

Second problem, the publishing status is a boolean. So if my riddle is unpublished the $value becomes FALSE and that means i am not able to set the field value, too.

Proposed resolution

1. problem: I took a look at the media core patch and found the sourceFieldChanged() method. I would like to implement it here, but return TRUE when there is no $original variable.
2. problem: Checking if $value is !== NULL

Remaining tasks

User interface changes

API changes

Data model changes