member isForeignKey of modelProperty class stays false

[imme-emosol]

member isForeignKey of modelProperty class stays false.
While Model::getRelationships(...) shows that there is a foreign key.
tested in ModelForm, snippet [ lines 27-32] :
var_dump( Model::getRelationships($model) );
$properties = Model::getProperties($model);
$this->inputs = array();
foreach($properties as $property) {
var_dump($property);