code: public void setResources(Collection<Resource> resources) {
          List<Resource> resourceList = new ArrayList<Resource>(resources);
          PolicyUtils.validateResourceList(resourceList);
          this.resources = resourceList;
      }
docs: Sets the resources associated with this policy statement. Resources are
  what a policy statement is allowing or denying access to, such as an
  Amazon SQS queue or an Amazon SNS topic.
  <p>
  Note that some services allow only one resource to be specified per
  policy statement.
  
  @param resources
  The resources associated with this policy statement.
  @throws IllegalArgumentException
  If the list of resources contains both a Resource and a NotResource