docs: private static ImmutableList<SoyMsgPart> buildMsgPartsForChildren(
        MsgBlockNode parent, MsgNode msgNode) {
  
      ImmutableList.Builder<SoyMsgPart> msgParts = ImmutableList.builder();
      doBuildMsgPartsForChildren(parent, msgNode, msgParts);
      return msgParts.build();
    }