src/Manager.php
public function hasManagerFile()
    {
        if (app('filesystem')->exists($this->directory.'manager.yml')) {
            return true;
        }

        $this->console->warn("No manager.yml file found in {$this->name} package.");

        return false;
    }
public function hasManagerFile()
    {
        if (app('filesystem')->exists($this->directory.'manager.yml')) {
            return true;
        }

        $this->console->warn("No manager.yml file found in {$this->name} package.");

        return false;
    }
Check manager file exists in package or not.

@return bool