all endpoints have its own class, no need to separate

src/Filter/PostFilter.php

-<?php
-
-/*
- * This file is part of the ONGR package.
- *
- * (c) NFQ Technologies UAB <info@nfq.com>
- *
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- */
-
-namespace ONGR\ElasticsearchDSL\Filter;
-
-use ONGR\ElasticsearchDSL\BuilderInterface;
-
-/**
- * Represents Elasticsearch "post_filter" filter.
- *
- * @link http://www.elastic.co/guide/en/elasticsearch/guide/current/_post_filter.html
- */
-class PostFilter implements BuilderInterface
-{
-    /**
-     * @var BuilderInterface
-     */
-    private $filter;
-
-    /**
-     * Sets a filter.
-     *
-     * @param BuilderInterface $filter
-     */
-    public function __construct(BuilderInterface $filter = null)
-    {
-        if ($this->filter !== null) {
-            $this->setFilter($filter);
-        }
-    }
-    
-    /**
-     * Checks if bool filter is relevant.
-     *
-     * @return bool
-     *
-     * @deprecated Will be removed in 1.0. Use getFilter() method.
-     */
-    public function isRelevant()
-    {
-        return isset($this->filter);
-    }
-
-    /**
-     * Returns filter.
-     *
-     * @return BuilderInterface
-     */
-    public function getFilter()
-    {
-        return $this->filter;
-    }
-
-    /**
-     * Sets filter.
-     *
-     * @param BuilderInterface $filter
-     */
-    public function setFilter(BuilderInterface $filter)
-    {
-        $this->filter = $filter;
-    }
-    
-    /**
-     * {@inheritdoc}
-     */
-    public function toArray()
-    {
-        return [$this->getFilter()->getType() => $this->getFilter()->toArray()];
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function getType()
-    {
-        return 'post_filter';
-    }
-}