public static VolleyMemoryCache getMemoryCache() {
    if (sMemoryCache == null) {
      sMemoryCache = new VolleyMemoryCache(ConfigConstants.MAX_MEMORY_CACHE_SIZE);
    }
    return sMemoryCache;
  }
Creates singletons of relevant volley classes
samples/comparison/src/main/java/com/facebook/samples/comparison/configs/volley/SampleVolleyFactory.java