Issue #3051231 by TR, cindytwilliams: Class names in *.routing.yml inconsistently use leading \

core/modules/block_content/block_content.routing.yml

core/modules/book/book.routing.yml

core/modules/comment/comment.routing.yml

core/modules/file/tests/file_test/file_test.routing.yml

.../modules/filter/tests/filter_test/filter_test.routing.yml

core/modules/jsonapi/jsonapi.routing.yml

core/modules/language/language.routing.yml

core/modules/locale/locale.routing.yml

core/modules/menu_ui/menu_ui.routing.yml

core/modules/node/node.routing.yml

core/modules/shortcut/shortcut.routing.yml

core/modules/simpletest/simpletest.routing.yml

core/modules/statistics/statistics.routing.yml

core/modules/system/system.routing.yml

...s/modules/js_webassert_test/js_webassert_test.routing.yml

...sts/modules/router_test_directory/router_test.routing.yml

...m/tests/modules/test_page_test/test_page_test.routing.yml

...modules/trusted_hosts_test/trusted_hosts_test.routing.yml

...ialization_test/vocabulary_serialization_test.routing.yml

.../update/tests/modules/update_test/update_test.routing.yml