import { ElementBuilder } from './ElementBuilder';
import { IBackboneElement, IExtension } from 'fhirtypes/dist/r4';
import { IBackboneBuilder } from './IBackboneBuilder';
/**
 * @description Backbone Element Builder
 * @description Base for elements defined inside a resource
 * @see {@link https://hl7.org/fhir/R4/backboneelement.html}
 *
 */
export declare class BackboneBuilder extends ElementBuilder implements IBackboneBuilder {
    private readonly backbone;
    constructor();
    /**
     * @description Extensions that cannot be ignored even if unrecognized
     * @param modifierExtension
     */
    addModifierExtension(modifierExtension: IExtension): this;
    /**
     * @description Returns the backbone element
     */
    build(): IBackboneElement;
}