diff --git a/src/Plugin/views/filter/SearchApiEntityBase.php b/src/Plugin/views/filter/SearchApiEntityBase.php
deleted file mode 100644
index b0df89f..0000000
--- a/src/Plugin/views/filter/SearchApiEntityBase.php
+++ /dev/null
@@ -1,224 +0,0 @@
-<?php
-
-namespace Drupal\search_api\Plugin\views\filter;
-
-use Drupal\Component\Utility\Tags;
-use Drupal\Core\Form\FormStateInterface;
-use Drupal\search_api\UncacheableDependencyTrait;
-
-/**
- * Provides a base class for filters on entity-typed fields.
- */
-abstract class SearchApiEntityBase extends SearchApiString {
-
-  use UncacheableDependencyTrait;
-
-  /**
-   * The query plugin for the current view.
-   *
-   * @var \Drupal\search_api\Plugin\views\query\SearchApiQuery
-   */
-  public $query = NULL;
-
-  /**
-   * If exposed form input was successfully validated, the entered entity IDs.
-   *
-   * @var array
-   */
-  protected $validatedExposedInput;
-
-  /**
-   * Validates entered entity labels and converts them to entity IDs.
-   *
-   * Since this can come from either the form or the exposed filter, this is
-   * abstracted out a bit so it can handle the multiple input sources.
-   *
-   * @param array $form
-   *   The form or form element for which any errors should be set.
-   * @param array $values
-   *   The entered user names to validate.
-   * @param \Drupal\Core\Form\FormStateInterface $form_state
-   *   The form state.
-   *
-   * @return array
-   *   The entity IDs corresponding to all entities that could be found.
-   */
-  abstract protected function validateEntityStrings(array &$form, array $values, FormStateInterface $form_state);
-
-  /**
-   * Transforms an array of entity IDs into a comma-separated list of labels.
-   *
-   * @param array $ids
-   *   The entity IDs to transform.
-   *
-   * @return string
-   *   A string containing the labels corresponding to the IDs, separated by
-   *   commas.
-   */
-  abstract protected function idsToString(array $ids);
-
-  /**
-   * {@inheritdoc}
-   */
-  public function operatorOptions() {
-    $operators = array(
-      '=' => $this->isMultiValued() ? $this->t('Is one of') : $this->t('Is'),
-      'all of' => $this->t('Is all of'),
-      '<>' => $this->isMultiValued() ? $this->t('Is not one of') : $this->t('Is not'),
-      'empty' => $this->t('Is empty'),
-      'not empty' => $this->t('Is not empty'),
-    );
-    if (!$this->isMultiValued()) {
-      unset($operators['all of']);
-    }
-    return $operators;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function defineOptions() {
-    $options = parent::defineOptions();
-
-    $options['expose']['multiple']['default'] = TRUE;
-
-    return $options;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function valueForm(&$form, FormStateInterface $form_state) {
-    parent::valueForm($form, $form_state);
-
-    if (!is_array($this->value)) {
-      $this->value = $this->value ? array($this->value) : array();
-    }
-
-    // Set the correct default value in case the admin-set value is used (and a
-    // value is present). The value is used if the form is either not exposed,
-    // or the exposed form wasn't submitted yet. (There doesn't seem to be an
-    // easier way to check for that.)
-    if ($this->value && (!$form_state->getUserInput() || !empty($form_state->getUserInput()['live_preview']))) {
-      $form['value']['#default_value'] = $this->idsToString($this->value);
-    }
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function valueValidate($form, FormStateInterface $form_state) {
-    if (!empty($form['value'])) {
-      $form_values = $form_state->getValues();
-      $value = $form_values['options']['value'];
-      $values = $this->isMultiValued($form_values['options']) ? Tags::explode($value) : array($value);
-      $ids = $this->validateEntityStrings($form['value'], $values, $form_state);
-
-      if ($ids) {
-        $value = $ids;
-        $form_state->setValue('value', $value);
-      }
-    }
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function acceptExposedInput($input) {
-    $rc = parent::acceptExposedInput($input);
-
-    if ($rc) {
-      // If we have previously validated input, override.
-      if ($this->validatedExposedInput) {
-        $this->value = $this->validatedExposedInput;
-      }
-    }
-
-    return $rc;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function validateExposed(&$form, FormStateInterface $form_state) {
-    if (empty($this->options['exposed']) || empty($this->options['expose']['identifier'])) {
-      return;
-    }
-
-    $identifier = $this->options['expose']['identifier'];
-    $input = $form_state->getValues()[$identifier];
-
-    if ($this->options['is_grouped'] && isset($this->options['group_info']['group_items'][$input])) {
-      $this->operator = $this->options['group_info']['group_items'][$input]['operator'];
-      $input = $this->options['group_info']['group_items'][$input]['value'];
-    }
-
-    $values = $this->isMultiValued() ? Tags::explode($input) : array($input);
-
-    if (!$this->options['is_grouped'] || ($this->options['is_grouped'] && ($input != 'All'))) {
-      $this->validatedExposedInput = $this->validateEntityStrings($form[$identifier], $values, $form_state);
-    }
-    else {
-      $this->validatedExposedInput = FALSE;
-    }
-  }
-
-  /**
-   * Determines whether multiple values can be entered into this filter.
-   *
-   * This is either the case if the form isn't exposed, or if the " Allow
-   * multiple selections" option is enabled.
-   *
-   * @param array $options
-   *   (optional) The options array to use. If not supplied, the options set on
-   *   this filter will be used.
-   *
-   * @return bool
-   *   TRUE if multiple values can be entered for this filter, FALSE otherwise.
-   */
-  protected function isMultiValued(array $options = array()) {
-    $options = $options ?: $this->options;
-    return empty($options['exposed']) || !empty($options['expose']['multiple']);
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function adminSummary() {
-    if (!is_array($this->value)) {
-      $this->value = $this->value ? array($this->value) : array();
-    }
-    $value = $this->value;
-    $this->value = empty($value) ? '' : $this->idsToString($value);
-    $ret = parent::adminSummary();
-    $this->value = $value;
-    return $ret;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function query() {
-    if ($this->operator === 'empty') {
-      $this->query->addCondition($this->realField, NULL, '=', $this->options['group']);
-    }
-    elseif ($this->operator === 'not empty') {
-      $this->query->addCondition($this->realField, NULL, '<>', $this->options['group']);
-    }
-    elseif (is_array($this->value)) {
-      $all_of = $this->operator === 'all of';
-      $operator = $all_of ? '=' : $this->operator;
-      if (count($this->value) == 1) {
-        $this->query->addCondition($this->realField, reset($this->value), $operator, $this->options['group']);
-      }
-      else {
-        $conditions = $this->query->createConditionGroup($operator === '<>' || $all_of ? 'AND' : 'OR');
-        foreach ($this->value as $value) {
-          $conditions->addCondition($this->realField, $value, $operator);
-        }
-        $this->query->addConditionGroup($conditions, $this->options['group']);
-      }
-    }
-  }
-
-}