backend-app-api: keep ServiceRegistry immutable

Signed-off-by: Vincenzo Scamporlino <vincenzos@spotify.com>

packages/backend-app-api/src/wiring/ServiceRegistry.ts

@@ -82,13 +82,6 @@ export class ServiceRegistry implements EnumerableServiceHolder {
     this.#implementations = new Map();
   }
 
-  add(serviceFactory: ServiceFactory) {
-    this.#providedFactories.set(
-      serviceFactory.service.id,
-      toInternalServiceFactory(serviceFactory),
-    );
-  }
-
   #resolveFactory(
     ref: ServiceRef<unknown>,
     pluginId: string,

packages/backend-app-api/src/wiring/types.ts

@@ -19,7 +19,6 @@ import {
   ExtensionPoint,
   ServiceRef,
   ServiceFactoryOrFunction,
-  ServiceFactory,
 } from '@backstage/backend-plugin-api';
 
 /**
@@ -40,7 +39,6 @@ export interface CreateSpecializedBackendOptions {
 
 export interface ServiceHolder {
   get<T>(api: ServiceRef<T>, pluginId: string): Promise<T> | undefined;
-  add(serviceFactory: ServiceFactory): void;
 }
 
 /**