code: @SuppressWarnings("unchecked")
      public <T> Set<T> getSet(String key) {
          return Reflection.toType(get(key), Set.class);
      }
docs: Get the set. Note you must be sure with the generic type, or a class cast exception will be thrown.
  
  @param key the argument name
  @param <T> the generic type
  @return the set representing the argument.