Data formatting using string spanning
Random random = new Random();
random.setSeed(System.nanoTime());


Don't put this inside here. I'm assuming that this method will end up being called more than once. If so, you don't want to be seeding and re-seeding the Random every call.

random should be moved to a field of the class. Also, I don't think you need to manually call Random.setSeed. See here for more details.



I don't know my Java 100%, but I think this might be a typo:

Pair&lt;SlideContent.SlideContentType, List&lt;SlideContent&gt;&gt;... pairs


I think it should be:

Pair&lt;SlideContent.SlideContentType&gt;, List&lt;SlideContent&gt;... pairs