Drupal 8 migration source to pull a node if a field is set or not

MyNodeWithField.php

<?php

namespace Drupal\my_migrate_common\Plugin\migrate\source;

use Drupal\migrate\Row;
use Drupal\node\Plugin\migrate\source\d7\Node as D7_Node;

/**
 * Source for node content depending on if a field is set or not.
 *
 * Use:
 *
 * ```yaml
 *  source:
 *   plugin: my_node_with_field
 *   field: field_to_split_on
 *   # Use present: true to pull nodes with the field populated, false for field empty.
 *   present: true
 *   # See core's node source for how these work:
 *   node_type: source_node_type
 *   translations: false
 *   ```
 *
 * @MigrateSource(
 *   id = "my_node_with_field"
 * )
 */
class MyNodeWithField extends D7_Node {

  public function query() {
    $query = parent::query();

    if (!empty($this->configuration['field'])) {
      // We can't inner join as field data may have multiple rows per entity.
      // Instead, we're going to use a subquery with distinct.
      $subquery = $this->select('field_data_' . $this->configuration['field'], 'f')
        ->fields('f', [
          'entity_id'
        ])
        ->distinct();

      $operator = 'IN';
      if (isset($this->configuration['present']) && $this->configuration['present'] == FALSE) {
        $operator = 'NOT IN';
      }

      $query->condition('n.nid', $subquery, $operator);
    }

    return $query;
  }
}