code: private <T> CategoryRegistry<T> getRegistry(final Class<T> pCategory) {
          @SuppressWarnings({"unchecked"})
          CategoryRegistry<T> registry = categoryMap.get(pCategory);
          if (registry == null) {
              throw new IllegalArgumentException("No such category: " + pCategory.getName());
          }
          return registry;
      }
docs: Gets the category registry for the given category.
  
  @param pCategory the category class
  @return the {@code CategoryRegistry} for the given category