protected function getFilesetsFromAnnotations($fileset_annotations) {
    $filesets = [];
    $this->logger->debug("Gathering filesets from annotated methods...");;
    foreach ($fileset_annotations as $class => $fileset) {
      if (class_exists($class)) {
        $fileset_class = new $class();
        $fileset_class->setConfig($this->config);
        foreach ($fileset as $id => $method_name) {
          $this->logger->debug("Calling $method_name on $class object...");
          if (method_exists($fileset_class, $method_name)) {
            $filesets[$id] = call_user_func_array([$fileset_class, $method_name],
              []);
          }
        }
      }
    }
    return $filesets;
  }