code: private DescribeTagsResponseType describeTags() {
          DescribeTagsResponseType ret = new DescribeTagsResponseType();
          ret.setRequestId(UUID.randomUUID().toString());
  
          TagSetType tagsSet = new TagSetType();
          for (MockTags mockVpc : mockTagsController.describeTags()) {
  
              for (String resourceId : mockVpc.getResourcesSet()) {
                  TagSetItemType tagItem = new TagSetItemType();
                  tagItem.setResourceId(resourceId);
                  tagItem.setKey(mockVpc.getTagSet().keySet()
                          .toArray(new String[mockVpc.getTagSet().size()])[0]);
                  tagItem.setValue(mockVpc.getTagSet().values()
                          .toArray(new String[mockVpc.getTagSet().size()])[0]);
                  tagsSet.getItem().add(tagItem);
              }
          }
  
          ret.setTagSet(tagsSet);
  
          return ret;
      }
docs: Handles "describeTags" request and returns response with a Tags.
  
  @return a DescribeTagsResponseType with our predefined Tags in aws-mock.properties (or if not overridden, as
  defined in aws-mock-default.properties)