code: private SingleOutputStreamOperator<T> setResources(ResourceSpec resources) {
  		Preconditions.checkNotNull(resources, "The resources must be not null.");
  		Preconditions.checkArgument(resources.isValid(), "The values in resources must be not less than 0.");
  
  		transformation.setResources(resources, resources);
  
  		return this;
  	}
docs: Sets the resources for this operator, the minimum and preferred resources are the same by default.
  
  @param resources The resources for this operator.
  @return The operator with set minimum and preferred resources.