Issue #3125391 by Beakerboy, daffie: Connection::query() return types…

… missing string

(cherry picked from commit b67ddac36203069e018d5999a32893b9c0a3550f)
(cherry picked from commit 9fcad9365d3548ca38a86daff5d57ae4180f312a)

lib/Drupal/Core/Database/Connection.php

@@ -585,7 +585,7 @@ protected function filterComment($comment = '') {
    *   Typically, $options['return'] will be set by a default or by a query
    *   builder, and should not be set by a user.
    *
-   * @return \Drupal\Core\Database\StatementInterface|int|null
+   * @return \Drupal\Core\Database\StatementInterface|int|string|null
    *   This method will return one of the following:
    *   - If either $options['return'] === self::RETURN_STATEMENT, or
    *     $options['return'] is not set (due to self::defaultOptions()),
@@ -594,7 +594,7 @@ protected function filterComment($comment = '') {
    *     returns the number of rows affected by the query
    *     (not the number matched).
    *   - If $options['return'] === self::RETURN_INSERT_ID,
-   *     returns the generated insert ID of the last query.
+   *     returns the generated insert ID of the last query as a string.
    *   - If either $options['return'] === self::RETURN_NULL, or
    *     an exception occurs and $options['throw_exception'] evaluates to FALSE,
    *     returns NULL.