
export interface APIKeyMixinProperties extends Partial<Pick<APIKeyMixin, "apiKey">> {}

/**
 * APIKeyMixin adds an `apiKey` property to layers and ensures that the key is included in all outgoing requests performed by those layers.
 *
 * @since 4.20
 */
export abstract class APIKeyMixin {
  constructor(...args: any[]);
  /**
   * An authorization string used to access a resource or service.
   * This property will append the API key to all requests made by the layer to the service.
   * [API keys](https://developers.arcgis.com/documentation/security-and-authentication/api-key-authentication/) are generated and managed in the portal.
   * An API key is tied explicitly to an ArcGIS account; it is also used to monitor service usage.
   * Setting a fine-grained API key on a specific class overrides the [global API key](https://developers.arcgis.com/javascript/latest/api-reference/esri-config.html#ConfigWithApiKey).
   *
   * If loading a secure layer with API authentication via a [PortalItem](https://developers.arcgis.com/javascript/latest/api-reference/esri-portal-PortalItem.html), the API key needs to be set on the layer's `portalItem` property.
   *
   * @since 4.20
   * @see [Item access privileges](https://developers.arcgis.com/documentation/security-and-authentication/api-key-authentication/api-key-credentials/#item-access-privileges)
   * @see [API key guide](https://developers.arcgis.com/javascript/latest/secure-resources/#api-keys)
   * @example
   * // set the api key to access a protected service
   * const layer = new FeatureLayer({
   *   url: serviceUrl,
   *   apiKey: "YOUR_API_KEY"
   * });
   */
  accessor apiKey: string | null | undefined;
}