BuildPDFWorkflow.php

<?php

namespace App\Workflows\BuildPDF;

use Workflow\ActivityStub;
use Workflow\Workflow;

class BuildPDFWorkflow extends Workflow
{
    public function execute()
    {
        $page1 = ActivityStub::make(ConvertURLActivity::class, 'https://example.com/');
        $page2 = ActivityStub::make(ConvertURLActivity::class, 'https://example.com/');

        $pages = yield ActivityStub::all([$page1, $page2]);

        $result = yield ActivityStub::make(MergePDFActivity::class, $pages);

        return $result;
    }
}