element with nested repeater

repeaterTest.php

<?php 

class repeaterTestElement extends \Bricks\Element {

  // Element properties
  public $category     = 'general';
  public $name         = 'testelement';
  public $icon         = 'ti-view-list-alt';
  public $css_selector = '';

  
  public function get_label() {
	  return esc_html__( 'Testing repeaters', 'extras' );
  }
  public function set_controls() {

    $this->controls['firstRepeater'] = [
      'tab'         => 'content',
      'label' => esc_html__( 'Add items', 'bricks' ),
      'title'    => esc_html__( 'Add item', 'bricks' ),
      'type'        => 'repeater',    			/* first repeater */
      'titleProperty' => 'label',
      'fields'      => [
        'title'    => [
          'label' => esc_html__( 'Some title', 'bricks' ),
          'type'  => 'text',
        ],
        'secondRepeater'    => [
          'label' => esc_html__( 'Add child items', 'bricks' ),
          'type'  => 'repeater',     			/* nested repeater */
          'fields'      => [
              'title'    => [
                'label' => esc_html__( 'Some title', 'bricks' ),
                'type'  => 'text',
              ],
            ]
          ]
         ]
      ];


  }

}