protected function save_default_attributes( $product, $request ) {
		// Update default attributes options setting.
		if ( isset( $request['default_attribute'] ) ) {
			$request['default_attributes'] = $request['default_attribute'];
		}

		if ( isset( $request['default_attributes'] ) && is_array( $request['default_attributes'] ) ) {
			$attributes         = $product->get_attributes();
			$default_attributes = array();

			foreach ( $request['default_attributes'] as $default_attr_key => $default_attr ) {
				if ( ! isset( $default_attr['name'] ) ) {
					continue;
				}

				$taxonomy = sanitize_title( $default_attr['name'] );

				if ( isset( $default_attr['slug'] ) ) {
					$taxonomy = $this->get_attribute_taxonomy_by_slug( $default_attr['slug'] );
				}

				if ( isset( $attributes[ $taxonomy ] ) ) {
					$_attribute = $attributes[ $taxonomy ];

					if ( $_attribute['is_variation'] ) {
						$value = '';

						if ( isset( $default_attr['option'] ) ) {
							if ( $_attribute['is_taxonomy'] ) {
								// Don't use wc_clean as it destroys sanitized characters.
								$value = sanitize_title( trim( stripslashes( $default_attr['option'] ) ) );
							} else {
								$value = wc_clean( trim( stripslashes( $default_attr['option'] ) ) );
							}
						}

						if ( $value ) {
							$default_attributes[ $taxonomy ] = $value;
						}
					}
				}
			}

			$product->set_default_attributes( $default_attributes );
		}

		return $product;
	}