79111 Migrate file_store to null safety (a: null-safety, cla: yes, team, tool, waiting for tree to go green)

79342 Migrate code_signing to null safety (a: null-safety, cla: yes, team, tool)

79346 Migrate event_printer and test_config to null safety (a: null-safety, cla: yes, team, tool, waiting for tree to go green)

79460 [Stocks App] NNBD migration, refresh gen-l10n (a: internationalization, a: null-safety, cla: yes, team, waiting for tree to go green)

79469 Migrate build_info to null safety (a: null-safety, cla: yes, team, tool)