30 files declare their use of ConverterBase in Drupal 7 to 8/9 Module Upgrader 8

Blocks.php in src/Plugin/DMU/Converter/Blocks.php

ContentRoute.php in src/Plugin/DMU/Routing/ContentRoute.php

EntityHooks.php in src/Plugin/DMU/Converter/EntityHooks.php

FunctionCallModifier.php in src/Plugin/DMU/Converter/Functions/FunctionCallModifier.php

Grep.php in src/Plugin/DMU/Converter/Grep.php

HookBoot.php in src/Plugin/DMU/Converter/HookBoot.php

HookEntityInfo.php in src/Plugin/DMU/Converter/HookEntityInfo.php

HookEntityTypeView.php in src/Plugin/DMU/Converter/HookEntityTypeView.php

HookExit.php in src/Plugin/DMU/Converter/HookExit.php

HookFieldAttachCreateBundle.php in src/Plugin/DMU/Converter/HookFieldAttachCreateBundle.php

HookFieldAttachDeleteBundle.php in src/Plugin/DMU/Converter/HookFieldAttachDeleteBundle.php

HookFieldAttachRenameBundle.php in src/Plugin/DMU/Converter/HookFieldAttachRenameBundle.php

HookFieldFormatterInfo.php in src/Plugin/DMU/Converter/HookFieldFormatterInfo.php

HookFieldWidgetInfo.php in src/Plugin/DMU/Converter/HookFieldWidgetInfo.php

HookFormAlter.php in src/Plugin/DMU/Converter/HookFormAlter.php

HookInit.php in src/Plugin/DMU/Converter/HookInit.php

HookLibrary.php in src/Plugin/DMU/Converter/HookLibrary.php

HookMenuAlter.php in src/Plugin/DMU/Converter/HookMenuAlter.php

HookNodePrepare.php in src/Plugin/DMU/Converter/HookNodePrepare.php

HookPermission.php in src/Plugin/DMU/Converter/HookPermission.php

HookURLOutboundAlter.php in src/Plugin/DMU/Converter/HookURLOutboundAlter.php

HookUserLogin.php in src/Plugin/DMU/Converter/HookUserLogin.php

HookWatchdog.php in src/Plugin/DMU/Converter/HookWatchdog.php

InfoToYAML.php in src/Plugin/DMU/Converter/InfoToYAML.php

Links.php in src/Plugin/DMU/Converter/Links.php

PSR4.php in src/Plugin/DMU/Converter/PSR4.php

Routing.php in src/Plugin/DMU/Converter/Routing.php

Tests.php in src/Plugin/DMU/Converter/Tests.php

UnitTests.php in src/Plugin/DMU/Converter/UnitTests.php

UserHooks.php in src/Plugin/DMU/Converter/UserHooks.php