code: public TaskSchedulerBuilder customizers(
  			Iterable<TaskSchedulerCustomizer> customizers) {
  		Assert.notNull(customizers, "Customizers must not be null");
  		return new TaskSchedulerBuilder(this.poolSize, this.awaitTermination,
  				this.awaitTerminationPeriod, this.threadNamePrefix,
  				append(null, customizers));
  	}
docs: Set the {@link TaskSchedulerCustomizer taskSchedulerCustomizers} that should be
  applied to the {@link ThreadPoolTaskScheduler}. Customizers are applied in the
  order that they were added after builder configuration has been applied. Setting
  this value will replace any previously configured customizers.
  @param customizers the customizers to set
  @return a new builder instance
  @see #additionalCustomizers(TaskSchedulerCustomizer...)