14 files declare their use of MaestroEngineTaskInterface in Maestro 3.x

MaestroAndTask.php in src/Plugin/EngineTasks/MaestroAndTask.php

MaestroBatchFunctionTask.php in src/Plugin/EngineTasks/MaestroBatchFunctionTask.php

MaestroContentTypeTask.php in src/Plugin/EngineTasks/MaestroContentTypeTask.php

MaestroEndTask.php in src/Plugin/EngineTasks/MaestroEndTask.php

MaestroIfTask.php in src/Plugin/EngineTasks/MaestroIfTask.php

MaestroInteractiveExampleTask.php in modules/examples/maestro_interactive_task_plugin_example/src/Plugin/EngineTasks/MaestroInteractiveExampleTask.php

MaestroInteractiveTask.php in src/Plugin/EngineTasks/MaestroInteractiveTask.php

MaestroManualWebTask.php in src/Plugin/EngineTasks/MaestroManualWebTask.php

MaestroNonInteractiveExampleTask.php in modules/examples/maestro_noninteractive_task_plugin_example/src/Plugin/EngineTasks/MaestroNonInteractiveExampleTask.php

MaestroOrTask.php in src/Plugin/EngineTasks/MaestroOrTask.php

MaestroSetProcessVariableTask.php in src/Plugin/EngineTasks/MaestroSetProcessVariableTask.php

MaestroSpawnSubFlowTask.php in src/Plugin/EngineTasks/MaestroSpawnSubFlowTask.php

MaestroStartTask.php in src/Plugin/EngineTasks/MaestroStartTask.php

MaestroWebformTask.php in modules/maestro_webform/src/Plugin/EngineTasks/MaestroWebformTask.php