protected function getExceptionMessageAppendix()
    {
        $tmp = [];
        if ($this->sourceBlueprint) { $tmp[] = 'Blueprint: ' . $this->sourceBlueprint->getName(); }
        if ($this->sourceType) { $tmp[] = 'Type:' . $this->sourceType; }
        if ($this->sourceKey) { $tmp[] = 'Key:' . $this->sourceKey; }
        if (count($tmp)) {
            return ' (' . implode(', ', $tmp) . ')';
        }
        return '';
    }