protected function get_to_array_excluded_properties() {

		/**
		 * Disable course property exclusion while running `toArray()`.
		 *
		 * This hook is intended to allow developers to retain the functionality implemented
		 * prior to the introduction of this hook.
		 *
		 * The LifterLMS developers consider the presence of these properties to be a bug but
		 * acknowledge that the removal of these properties could be seen as a backwards incompatible
		 * "feature" removal.
		 *
		 * This hook disables the exclusion of the following properties: 'average_grade', 'average_progress',
		 * 'enrolled_students', 'last_data_calc_run', and 'temp_calc_data'. Any excluded properties added in the
		 * future will not be excluded when using this hook.
		 *
		 * @example `add_filter( 'llms_course_to_array_disable_prop_exclusion', '__return_true' );`
		 *
		 * @since 5.4.1
		 *
		 * @param boolean $disable Whether or not to disable property exclusions.
		 */
		$disable = apply_filters( 'llms_course_to_array_disable_prop_exclusion', false );
		if ( $disable ) {
			return array();
		}

		return array(
			'average_grade',
			'average_progress',
			'enrolled_students',
			'last_data_calc_run',
			'temp_calc_data',
		);
	}