protected function clean_custom_array_property( $property, $flip = false, $to_lower = false ) {
		if ( is_bool( $property ) ) {
			// Allow for resetting in the unit tests.
			return array();
		}

		if ( is_string( $property ) ) {
			$property = explode( ',', $property );
		}

		$property = array_filter( array_map( 'trim', $property ) );

		if ( true === $to_lower ) {
			$property = array_map( 'strtolower', $property );
		}

		if ( true === $flip ) {
			$property = array_fill_keys( $property, false );
		}

		return $property;
	}