code: public Datatype.Builder clearNestedClasses() {
      if (nestedClasses instanceof ImmutableList) {
        nestedClasses = ImmutableList.of();
      } else {
        nestedClasses.clear();
      }
      return (Datatype.Builder) this;
    }
docs: Clears the list to be returned from {@link Datatype#getNestedClasses()}.
  
  @return this {@code Builder} object