public function calculateChangeSet()
    {
        if (false === $this->isDirty()) {
            return [];
        }
        return [
            'old' => empty($this->original) ? null : $this->original,
            'new' => empty($this->models) ? null : $this->models,
        ];
    }
public function calculateChangeSet()
    {
        if (false === $this->isDirty()) {
            return [];
        }
        return [
            'old' => empty($this->original) ? null : $this->original,
            'new' => empty($this->models) ? null : $this->models,
        ];
    }
public function calculateChangeSet ( ) { if ( false === $ this -> isDirty ( ) ) { return [ ] ; } return [ 'old' => empty ( $ this -> original ) ? null : $ this -> original , 'new' => empty ( $ this -> models ) ? null : $ this -> models , ] ; }
Calculates the change set of this collection.

@return  array
Calculates the change set of this collection .