chore: license comment

logger.go

manager.go

manager_test.go

persistence.go

persistence_test.go

queue.go

queue_test.go

runnable-counter.go

runnable-counter_test.go

runnable-dummy.go

runnable-dummy_test.go

runnable-fileoperation.go

runnable-fileoperation_test.go

runnable-gorm.go

runnable-gorm_test.go

runnable-http.go

runnable-http_test.go

runnable-mail.go

runnable-mail_test.go

runnable-sftp.go