code: public static StringBuilder appendColumns(StringBuilder builder, List<String> columns, String selectQuery,
              CQLTranslator translator)
      {
          if (columns != null)
          {
              for (String column : columns)
              {
                  translator.appendColumnName(builder, column);
                  builder.append(",");
              }
          }
          if (builder.lastIndexOf(",") != -1)
          {
              builder.deleteCharAt(builder.length() - 1);
              selectQuery = StringUtils.replace(selectQuery, CQLTranslator.COLUMNS, builder.toString());
          }
  
          builder = new StringBuilder(selectQuery);
          return builder;
      }
docs: Append columns.
  
  @param builder
  the builder
  @param columns
  the columns
  @param selectQuery
  the select query
  @param translator
  the translator