public function getRegisteredListeners($plugin = null)
{
if ($plugin !== null) {
$listeners = [];
foreach ($this->getRegisteredListeners(null) as $hash => $listener) {
if ($listener->getPlugin() === $plugin) {
$listeners[$hash] = $plugin;
}
}
return $listeners;
} else {
while (($handlers = $this->handlers) === null) {
$this->bake();
}
return $handlers;
}
}