return array_values( array_unique( $images ) );
	}

	/**
	 * Called by toArray to add custom fields via get_post_meta()
	 *
	 * Removes all custom props registered to the $this->properties automatically.
	 * Also removes some fields used by the WordPress core that don't hold necessary data.
	 * Extending classes may override this class to exclude, extend, or modify the custom fields for a post type.
	 *
	 * @since 3.16.11
	 * @since 3.30.0 Use `maybe_unserialize()` to ensure array data is accessible as an array.
	 * @since 3.30.2 Add filter to allow 3rd parties to prevent a field from being added to the custom field array.
	 *
	 * @param array $arr Existing post array.
	 * @return array
	 */
	protected function toArrayCustom( $arr ) {

		// Build an array of keys that are registered or can be excluded as a custom field.
		$props = array_keys( $this->get_properties() );
		foreach ( $props as &$prop ) {
			$prop = $this->meta_prefix . $prop;
		}
		$props[] = '_edit_lock';
		$props[] = '_edit_last';

		// Get all meta data.
		$custom = array();
		foreach ( get_post_meta( $this->get( 'id' ) ) as $key => $vals ) {

			// Skip registered fields or fields 3rd parties want to skip.
			/**
			 * Filters whether the custom field should be excluded in the array representation of the post model
			 *
			 * The dynamic portion of this hook, `$this->model_post_type`, refers to the model's post type. For example "course",
			 * "lesson", "membership", etc...
			 *
			 * @since 3.30.2
			 *