protected function update_attributes( &$product, $force = false ) {
		$changes = $product->get_changes();

		if ( $force || array_key_exists( 'attributes', $changes ) ) {
			$attributes  = $product->get_attributes();
			$meta_values = array();

			if ( $attributes ) {
				foreach ( $attributes as $attribute_key => $attribute ) {
					$value = '';

					if ( is_null( $attribute ) ) {
						if ( taxonomy_exists( $attribute_key ) ) {
							// Handle attributes that have been unset.
							wp_set_object_terms( $product->get_id(), array(), $attribute_key );
						} elseif ( taxonomy_exists( urldecode( $attribute_key ) ) ) {
							// Handle attributes that have been unset.
							wp_set_object_terms( $product->get_id(), array(), urldecode( $attribute_key ) );
						}
						continue;

					} elseif ( $attribute->is_taxonomy() ) {
						wp_set_object_terms( $product->get_id(), wp_list_pluck( (array) $attribute->get_terms(), 'term_id' ), $attribute->get_name() );
					} else {
						$value = wc_implode_text_attributes( $attribute->get_options() );
					}

					// Store in format WC uses in meta.
					$meta_values[ $attribute_key ] = array(
						'name'         => $attribute->get_name(),
						'value'        => $value,
						'position'     => $attribute->get_position(),
						'is_visible'   => $attribute->get_visible() ? 1 : 0,
						'is_variation' => $attribute->get_variation() ? 1 : 0,
						'is_taxonomy'  => $attribute->is_taxonomy() ? 1 : 0,
					);
				}
			}
			// Note, we use wp_slash to add extra level of escaping. See https://codex.wordpress.org/Function_Reference/update_post_meta#Workaround.
			$this->update_or_delete_post_meta( $product, '_product_attributes', wp_slash( $meta_values ) );
		}
	}