code: public static List<String> getColumnListFromQuery(String query) {
      if (Strings.isNullOrEmpty(query)) {
        return null;
      }
      String queryLowerCase = query.toLowerCase();
      int startIndex = queryLowerCase.indexOf("select ") + 7;
      int endIndex = queryLowerCase.indexOf(" from ");
      if (startIndex < 0 || endIndex < 0) {
        return null;
      }
      String[] inputQueryColumns = query.substring(startIndex, endIndex).toLowerCase().replaceAll(" ", "").split(",");
      return Arrays.asList(inputQueryColumns);
    }
docs: get column list from the user provided query to build schema with the respective columns
  @param input query
  @return list of columns