export declare class FilterUtil {
    private static filterQueryMappers;
    private static filterQueryKeys;
    private static filterQueryOperators;
    private static defaultFilterOperator;
    static getQueryKeys(): string[];
    static isQueryKey(key: string): boolean;
    static getQueryOperators(): string[];
    static isQueryOperator(operator: string): boolean;
    static transformMongooseFilter(filter: any): any;
    static transformTypeormFilter(filter: any, modelName: string): any;
    private static removeEmptyQueryArrays;
}