Custom generator command, is not stopping when create file that already exists

So, i'm trying to use PHP Artisan on Laravel 5.3 to create a class file for each Cron configuration in my project, i'm doing this because it's possible that i'll want to create these files from a separate GUI in the future.

I'm able to create the files, and i'm using stubs so everything gets generated as it should, the problem however is that for some reason, if a file, say "cron_4" exists and i call my custom command php artisan make:cron cron_4 it'll allow me to do so and will simply overwrite the existing file.

This is my code so far. Any ideas as to what i might be doing wrong here?

<?php

namespace App\Console\Commands;

use Illuminate\Console\GeneratorCommand;
use Symfony\Component\Console\Input\InputOption;

class CronMakeCommand extends GeneratorCommand
{
/**
 * The console command name.
 *
 * @var string
 */
protected $name = 'make:cron';

/**
 * The console command description.
 *
 * @var string
 */
protected $description = 'Create a new Cron class';

/**
 * The type of class being generated.
 *
 * @var string
 */
protected $type = 'Cron';

/**
 * Get the stub file for the generator.
 *
 * @return string
 */
protected function getStub()
{
    return __DIR__.'/stubs/cron.stub';
}

/**
 * Get the default namespace for the class.
 *
 * @param  string  $rootNamespace
 * @return string
 */
protected function getDefaultNamespace($rootNamespace)
{
    return $rootNamespace.'\Crons';
}

/**
 * Execute the console command.
 *
 * @return void
 */
public function fire()
{
    if (! $this->option('id')) {
        return $this->error('Missing required option: --id');
    }

    parent::fire();
}

/**
 * Replace the class name for the given stub.
 *
 * @param  string  $stub
 * @param  string  $name
 * @return string
 */
protected function replaceClass($stub, $name)
{
    $stub = parent::replaceClass($stub, $name);

    return str_replace('dummy:cron', 'Cron_' . $this->option('id'), $stub);
}

/**
 * Determine if the class already exists.
 *
 * @param  string  $rawName
 * @return bool
 */
protected function alreadyExists($rawName)
{
    return class_exists($rawName);
}

/**
 * Get the console command options.
 *
 * @return array
 */
protected function getOptions()
{
    return [
        ['id', null, InputOption::VALUE_REQUIRED, 'The ID of the Cron being Generated.'],
    ];
}
}

via Chebli Mohamed