quisse

<?php

namespace Vendor\Module\Plugin;

use Magento\Catalog\Helper\Output;

class OutputPlugin {

	public function beforeCollectHandlers(Output $outputHelper) {
		$outputHelper->addHandler('productAttribute', $this);

quisse

<?php

namespace Vendor\Module\Plugin;

use Magento\Catalog\Helper\Output;

class OutputPlugin {

	// this plugin method should be on a method which collects all handlers and isn't called everytime the handlers are processed
	public function beforeProcess(Output $outputHelper, $method, $result, $params) {