/**
 * NestJS-specific query processing based on the output of `ctx.switchToHttp().getRequest().query`.
 *
 * We handle the following cases:
 * 1. For `?filter[age]=10,20`, `value` is `10,20`, which we transform to `{eq: "10,20"}`.
 * 2. For `?filter[age]=20`, `value` is `20`, which we transform to `{eq: "20"}`.
 * 3. For `?filter[age][gt]=10&filter[age]=20`, `value` may be `[{gt: "10"}, "20"]` or
 *    `{"20": true, gt: "10"}`, which we transform to `{eq: "20", gt: "10"}`.
 * 4. For `?filter[age]=10&filter[age]=20`, `value` is `['10', '20']`, which we transform to `{eq:
 *    "10,20"}`.
 * 5. For `?filter[age][gt]=5&filter[age]=10&filter[age]=20`, `value` is `{'0': '10', '1': '20', gt:
 *    '5'}`, which we transform to `{eq: "10,20", gt: "5"}`.
 */
export declare function queryFilterPreprocessor(value: unknown): Record<string, string>;