check_is_comment_content_allowed example

$prepared_comment = $this->prepare_item_for_database( $request );
        if ( is_wp_error( $prepared_comment ) ) {
            return $prepared_comment;
        }

        $prepared_comment['comment_type'] = 'comment';

        if ( ! isset( $prepared_comment['comment_content'] ) ) {
            $prepared_comment['comment_content'] = '';
        }

        if ( ! $this->check_is_comment_content_allowed( $prepared_comment ) ) {
            return new WP_Error(
                'rest_comment_content_invalid',
                __( 'Invalid comment content.' ),
                array( 'status' => 400 )
            );
        }

        // Setting remaining values before wp_insert_comment so we can use wp_allow_comment().         if ( ! isset( $prepared_comment['comment_date_gmt'] ) ) {
            $prepared_comment['comment_date_gmt'] = current_time( 'mysql', true );
        }