9 files declare their use of Merge

Connection.php in core/tests/fixtures/database_drivers/custom/fake/Connection.php
Connection.php in core/lib/Drupal/Core/Database/Connection.php
DatabaseStorage.php in core/lib/Drupal/Core/KeyValueStore/DatabaseStorage.php
Merge.php in core/modules/sqlite/src/Driver/Database/sqlite/Merge.php
Merge.php in core/modules/mysql/src/Driver/Database/mysql/Merge.php
Merge.php in core/modules/pgsql/src/Driver/Database/pgsql/Merge.php
Merge.php in core/tests/fixtures/database_drivers/module/core_fake/src/Driver/Database/CoreFakeWithAllCustomClasses/Merge.php
MergeTest.php in core/tests/Drupal/KernelTests/Core/Database/MergeTest.php
StubConnection.php in core/tests/Drupal/Tests/Core/Database/Stub/StubConnection.php

Buggy or inaccurate documentation? Please file an issue. Need support? Need help programming? Connect with the Drupal community.