code: private static String buildGoogMsgContentStr(
        ImmutableList<SoyMsgPart> msgParts, boolean doUseBracedPhs) {
  
      msgParts = IcuSyntaxUtils.convertMsgPartsToEmbeddedIcuSyntax(msgParts);
  
      StringBuilder msgStrSb = new StringBuilder();
  
      for (SoyMsgPart msgPart : msgParts) {
  
        if (msgPart instanceof SoyMsgRawTextPart) {
          msgStrSb.append(((SoyMsgRawTextPart) msgPart).getRawText());
  
        } else if (msgPart instanceof SoyMsgPlaceholderPart) {
          String placeholderName = ((SoyMsgPlaceholderPart) msgPart).getPlaceholderName();
          if (doUseBracedPhs) {
            // Add placeholder to message text.
            msgStrSb.append("{").append(placeholderName).append("}");
  
          } else {
            // For goog.getMsg(), we must change the placeholder name to lower camel-case format.
            String googMsgPlaceholderName = genGoogMsgPlaceholderName(placeholderName);
            // Add placeholder to message text. Note the '$' for goog.getMsg() syntax.
            msgStrSb.append("{$").append(googMsgPlaceholderName).append("}");
          }
  
        } else {
          throw new AssertionError("unexpected part: " + msgPart);
        }
      }
  
      return msgStrSb.toString();
    }
docs: Builds the message content string for a goog.getMsg() call.
  
  @param msgParts The parts of the message.
  @param doUseBracedPhs Whether to use braced placeholders.
  @return The message content string for a goog.getMsg() call.