import { FirestoreModelFieldValueConverter, ModelFieldValueConverter } from "../model_field_value_converter";
/**
 * Null ModelFieldValueConverter.
 *
 * Null用のModelFieldValueConverter。
 */
export declare class ModelNullConverter extends ModelFieldValueConverter {
    /**
     * Null ModelFieldValueConverter.
     *
     * Null用のModelFieldValueConverter。
     */
    constructor();
    type: string;
    convertFrom(key: string, value: any, original: {
        [field: string]: any;
    }): {
        [field: string]: any;
    } | null;
    convertTo(key: string, value: any, original: {
        [field: string]: any;
    }): {
        [field: string]: any;
    } | null;
}
/**
 * FirestoreConverter for [Null].
 *
 * [Null]用のFirestoreConverter。
 */
export declare class FirestoreNullConverter extends FirestoreModelFieldValueConverter {
    /**
     * FirestoreConverter for [Null].
     *
     * [Null]用のFirestoreConverter。
     */
    constructor();
    type: string;
    convertFrom(key: string, value: any, original: {
        [field: string]: any;
    }, firestoreInstance: FirebaseFirestore.Firestore): {
        [field: string]: any;
    } | null;
    convertTo(key: string, value: any, original: {
        [field: string]: any;
    }, firestoreInstance: FirebaseFirestore.Firestore): {
        [field: string]: any;
    } | null;
}