8 files declare their use of TransactionManagerBase

DriverSpecificTransactionTestBase.php in core/tests/Drupal/KernelTests/Core/Database/DriverSpecificTransactionTestBase.php
StubTransactionManager.php in core/tests/Drupal/Tests/Core/Database/Stub/StubTransactionManager.php
TransactionManager.php in core/modules/pgsql/src/Driver/Database/pgsql/TransactionManager.php
TransactionManager.php in core/modules/mysqli/src/Driver/Database/mysqli/TransactionManager.php
TransactionManager.php in core/modules/sqlite/src/Driver/Database/sqlite/TransactionManager.php
TransactionManager.php in core/modules/mysql/src/Driver/Database/mysql/TransactionManager.php
TransactionManagerTest.php in core/tests/Drupal/Tests/Core/Database/TransactionManagerTest.php
TransactionTest.php in core/tests/Drupal/KernelTests/Core/Database/TransactionTest.php

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