public Builder addArgs(
          int index, main.Messages.Argument.Builder builderForValue) {
        if (argsBuilder_ == null) {
          ensureArgsIsMutable();
          args_.add(index, builderForValue.build());
          onChanged();
        } else {
          argsBuilder_.addMessage(index, builderForValue.build());
        }
        return this;
      }