docs: public static String getRetRequiredCheck(String express, Field field) {
          String code = "if (CodedConstant.isNull(" + express + ")) {\n";
          code += "throw new UninitializedMessageException(CodedConstant.asList(\"" + field.getName() + "\"))"
                  + ClassCode.JAVA_LINE_BREAK;
          code += "}\n";
  
          return code;
      }