private function findChildNamespaces() {
        $currentNamespaceFqsen = (string)$this->currentNamespace->getFqsen();
        /** @var Namespace_ $namespace */
        foreach ($this->namespaces as $namespace) {
            // check if not root and doesn't start with current namespace
            if ($currentNamespaceFqsen !== '\\' && strpos((string)$namespace->getFqsen(), $currentNamespaceFqsen . '\\') !== 0) {
                continue;
            }
            if ((string)$namespace->getFqsen() !== $currentNamespaceFqsen && strpos((string)$namespace->getFqsen(), $currentNamespaceFqsen) === 0) {
                // only keep first level children
                $childrenPath = substr((string)$namespace->getFqsen(), strlen((string)$this->currentNamespace->getFqsen()) + 1);
                if (strpos($childrenPath, '\\') === false) {
                    $this->childNamespaces[] = $namespace;
                }
            }
        }
    }