M2 - What is the error in my observer

[Aveeva]

I want to get selected attributes in product listing page using observer,

app\code\Zero\DescBlock\registration.php

<?php
\Magento\Framework\Component\ComponentRegistrar::register(

    \Magento\Framework\Component\ComponentRegistrar::MODULE,

    'Zero_DescBlock', __DIR__ );

app\code\Zero\DescBlock\etc\frontend\events.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="catalog_product_collection_load_before">
         <observer name="ChangeDescBlock" instance="Zero\DescBlock\Observer\Data" />
    </event>
</config>

app\code\Zero\DescBlock\etc\module.xml

<?xml version="1.0" ?>
    <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
    <module name="Zero_DescBlock" setup_version="1.0.0"/>
    <!-- <sequence>
        <module name="Magento_Catalog">
    </sequence> -->
</config>

app\code\Zero\DescBlock\Observer\Data.php

<?php

namespace Zero\DescBlock\Observer;

use Magento\Framework\Event\ObserverInterface;
use Magento\Catalog\Model\Layer\Resolver as LayerResolver;

class Data implements ObserverInterface
{
    /**
     * @var \Magento\Catalog\Model\Layer\Category
     */
    protected $catalogLayer;

    /**
     * @param LayerResolver $layerResolver,
     */
    public function __construct(        LayerResolver $layerResolver
    ) {
        $this->catalogLayer = $layerResolver->get();
    }

    public function execute(\Magento\Framework\Event\Observer $observer)
    {
        // Get selected filters
        $layer         = $this->catalogLayer;
        $activeFilters = $layer->getState()->getFilters();
        $this->logger->info(print_r( $activeFilters, true));

    }
}

The logger not return selected attributes.