docs: public Datatype.Builder addAllNestedClasses(Spliterator<? extends Excerpt> elements) {
      if ((elements.characteristics() & Spliterator.SIZED) != 0) {
        long elementsSize = elements.estimateSize();
        if (elementsSize > 0 && elementsSize <= Integer.MAX_VALUE) {
          if (nestedClasses instanceof ImmutableList) {
            nestedClasses = new ArrayList<>(nestedClasses);
          }
          ((ArrayList<?>) nestedClasses).ensureCapacity(nestedClasses.size() + (int) elementsSize);
        }
      }
      elements.forEachRemaining(this::addNestedClasses);
      return (Datatype.Builder) this;
    }