@SafeVarargs
  public static <T> Iterable<T> $(Iterable<? extends T>... iterables) {
    return Iterables.concat(iterables);
  }
Effect of using this method is boxing in calling code.
@param value value
@param <T> result type
@return the same value.
generator/src/org/immutables/generator/Intrinsics.java