code: public <T extends ThreadPoolTaskExecutor> T build(Class<T> taskExecutorClass) {
  		return configure(BeanUtils.instantiateClass(taskExecutorClass));
  	}
docs: Build a new {@link ThreadPoolTaskExecutor} instance of the specified type and
  configure it using this builder.
  @param <T> the type of task executor
  @param taskExecutorClass the template type to create
  @return a configured {@link ThreadPoolTaskExecutor} instance.
  @see #build()
  @see #configure(ThreadPoolTaskExecutor)