public function getStaticProperties()
    {
        if ($this->staticProperties === null) {
            // lazy load class properties list
            foreach ($this->node->stmts as $stmt) {
                if ($stmt instanceof Node\Stmt\Property) {
                    if ($stmt->isStatic() === false) {
                        continue;
                    }
                    foreach ($stmt->props as $prop) {
                        $this->staticProperties[] = new PropertyModel($this, $prop);
                    }
                }
            }
        }
        return $this->staticProperties;
    }