Specifies the java.util.Executor instance to use when invoking asynchronous methods.
If not provided, an instance of org.springframework.core.task.SimpleAsyncTaskExecutor
will be used by default.
Specifies the org.springframework.scheduling.TaskScheduler or
java.util.ScheduledExecutorService instance to use when invoking scheduled
methods. If no reference is provided, a TaskScheduler backed by a single
thread scheduled executor will be used.