code: public static MsgPartsAndIds buildMsgPartsAndComputeMsgIdForDualFormat(MsgNode msgNode) {
  
      if (msgNode.isPlrselMsg()) {
        MsgPartsAndIds mpai = buildMsgPartsAndComputeMsgIds(msgNode, true);
        return new MsgPartsAndIds(mpai.parts, mpai.idUsingBracedPhs, -1L);
      } else {
        return buildMsgPartsAndComputeMsgIds(msgNode, false);
      }
    }
docs: Builds the list of SoyMsgParts and computes the unique message id for the given MsgNode,
  assuming a specific dual format.
  
  <p>Note: The field {@code idUsingBracedPhs} in the return value is simply set to -1L.
  
  @param msgNode The message parsed from the Soy source.
  @return A {@code MsgPartsAndIds} object, assuming a specific dual format, with field {@code
  idUsingBracedPhs} set to -1L.