code: public TaskExecutorBuilder customizers(Iterable<TaskExecutorCustomizer> customizers) {
  		Assert.notNull(customizers, "Customizers must not be null");
  		return new TaskExecutorBuilder(this.queueCapacity, this.corePoolSize,
  				this.maxPoolSize, this.allowCoreThreadTimeOut, this.keepAlive,
  				this.awaitTermination, this.awaitTerminationPeriod, this.threadNamePrefix,
  				this.taskDecorator, append(null, customizers));
  	}
docs: Set the {@link TaskExecutorCustomizer TaskExecutorCustomizers} that should be
  applied to the {@link ThreadPoolTaskExecutor}. 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(TaskExecutorCustomizer...)