docs: private Expression generateMsgGroupVariable(MsgFallbackGroupNode node, String tmpVarName) {
      checkState(node.numChildren() == 2);
  
      // Generate the goog.getMsg calls for all children.
      GoogMsgCodeGenInfo primaryCodeGenInfo =
          genGoogGetMsgCallHelper(buildGoogMsgVarNameHelper(node.getChild(0)), node.getChild(0));
      GoogMsgCodeGenInfo fallbackCodeGenInfo =
          genGoogGetMsgCallHelper(buildGoogMsgVarNameHelper(node.getChild(1)), node.getChild(1));
  
      // Declare a temporary variable to hold the getMsgWithFallback() call so that we can apply any
      // MessageFormats from any of the fallbacks.  This is also the variable name that we return to
      // the caller.
      Expression selectedMsg =
          VariableDeclaration.builder(tmpVarName)
              .setRhs(
                  Expression.dottedIdNoRequire("goog.getMsgWithFallback")
                      .call(primaryCodeGenInfo.googMsgVar, fallbackCodeGenInfo.googMsgVar))
              .build()
              .ref();
  
      // We use id() here instead of using the corresponding code chunks because the stupid
      // jscodebuilder system causes us to regenerate the msg vars multiple times because it doesn't
      // detect that they were already generated.
      // TODO(b/33382980): clean this up
      Expression isPrimaryMsgInUse =
          Expression.id(tmpVarName).doubleEquals(Expression.id(primaryCodeGenInfo.googMsgVarName));
      translationContext.soyToJsVariableMappings().setIsPrimaryMsgInUse(node, isPrimaryMsgInUse);
      if (primaryCodeGenInfo.placeholders == null && fallbackCodeGenInfo.placeholders == null) {
        // all placeholders have already been substituted, just return
        return selectedMsg;
      }
      // Generate the goog.i18n.MessageFormat calls for child plural/select messages (if any), each
      // wrapped in an if-block that will only execute if that child is the chosen message.
      Statement condition;
      if (primaryCodeGenInfo.placeholders != null) {
        ConditionalBuilder builder =
            Statement.ifStatement(
                selectedMsg.doubleEquals(primaryCodeGenInfo.googMsgVar),
                selectedMsg.assign(getMessageFormatCall(primaryCodeGenInfo)).asStatement());
        if (fallbackCodeGenInfo.placeholders != null) {
          builder.setElse(
              selectedMsg.assign(getMessageFormatCall(fallbackCodeGenInfo)).asStatement());
        }
        condition = builder.build();
      } else {
        condition =
            Statement.ifStatement(
                    selectedMsg.doubleEquals(fallbackCodeGenInfo.googMsgVar),
                    selectedMsg.assign(getMessageFormatCall(fallbackCodeGenInfo)).asStatement())
                .build();
      }
      return Expression.id(tmpVarName).withInitialStatement(condition);
    }