diff --git a/plugins/permission-node/src/integration/createPermissionIntegrationRouter.test.ts b/plugins/permission-node/src/integration/createPermissionIntegrationRouter.test.ts
index 323a56329d..c369c8be95 100644
--- a/plugins/permission-node/src/integration/createPermissionIntegrationRouter.test.ts
+++ b/plugins/permission-node/src/integration/createPermissionIntegrationRouter.test.ts
@@ -92,7 +92,7 @@ const defaultMockedGetResources2: CreatePermissionIntegrationRouterResourceOptio
   resourceRefs.map(resourceRef => ({ id: resourceRef })),
 );
 
-const mockedResourceOptions = {
+const mockedOptionResources: OptionResources = {
   resources: [
     {
       resourceType: 'test-resource',
@@ -125,17 +125,6 @@ const createApp = (
   return express().use(router);
 };
 
-const createAppWithResources = (
-  resourceOptions:
-    | CreatePermissionIntegrationRouterResourceOptions<string, any>
-    | OptionResources<string, any>,
-) => {
-  const router = createPermissionIntegrationRouter(
-    resourceOptions as Parameters<typeof createPermissionIntegrationRouter>[0],
-  );
-  return express().use(router);
-};
-
 describe('createPermissionIntegrationRouter', () => {
   afterEach(() => {
     jest.clearAllMocks();
@@ -240,7 +229,11 @@ describe('createPermissionIntegrationRouter', () => {
 
       (defaultMockedGetResources1 as jest.Mock).mockClear();
 
-      response = await request(createAppWithResources(mockedResourceOptions))
+      const app = express().use(
+        createPermissionIntegrationRouter(mockedOptionResources),
+      );
+
+      response = await request(app)
         .post('/.well-known/backstage/permissions/apply-conditions')
         .send({
           items: [
@@ -459,7 +452,11 @@ describe('createPermissionIntegrationRouter', () => {
       let response: Response;
 
       beforeEach(async () => {
-        response = await request(createAppWithResources(mockedResourceOptions))
+        const app = express().use(
+          createPermissionIntegrationRouter(mockedOptionResources),
+        );
+
+        response = await request(app)
           .post('/.well-known/backstage/permissions/apply-conditions')
           .send({
             items: [
@@ -763,11 +760,13 @@ describe('createPermissionIntegrationRouter', () => {
 
     it('returns 501 with no getResources implementation', async () => {
       const response = await request(
-        createAppWithResources({
-          resourceType: 'test-resource',
-          permissions: [testPermission],
-          rules: [testRule1, testRule2],
-        }),
+        express().use(
+          createPermissionIntegrationRouter({
+            resourceType: 'test-resource',
+            permissions: [testPermission],
+            rules: [testRule1, testRule2],
+          }),
+        ),
       )
         .post('/.well-known/backstage/permissions/apply-conditions')
         .send({
@@ -841,7 +840,7 @@ describe('createPermissionIntegrationRouter', () => {
     });
     it('returns a list of permissions and rules used by a given backend that was created with an array of resource options', async () => {
       const response = await request(
-        createAppWithResources(mockedResourceOptions),
+        express().use(createPermissionIntegrationRouter(mockedOptionResources)),
       ).get('/.well-known/backstage/permissions/metadata');
 
       expect(response.status).toEqual(200);
diff --git a/plugins/permission-node/src/integration/createPermissionIntegrationRouter.ts b/plugins/permission-node/src/integration/createPermissionIntegrationRouter.ts
index d015734d91..1ac53a4721 100644
--- a/plugins/permission-node/src/integration/createPermissionIntegrationRouter.ts
+++ b/plugins/permission-node/src/integration/createPermissionIntegrationRouter.ts
@@ -207,16 +207,46 @@ export type CreatePermissionIntegrationRouterResourceOptions<
   ) => Promise<Array<TResource | undefined>>;
 };
 
-/**
- * Options for creating a permission integration router
- *
- * @public
- */
-export type OptionResources<TResourceType extends string, TResource> = {
-  resources:
-    | { permissions: Array<Permission> }
-    | CreatePermissionIntegrationRouterResourceOptions<TResourceType, TResource>
-    | Array<CreatePermissionIntegrationRouterResourceOptions<string, any>>;
+export type OptionResources<
+  TResourceType1 extends string = string,
+  TResource1 = any,
+  TResourceType2 extends string = string,
+  TResource2 = any,
+  TResourceType3 extends string = string,
+  TResource3 = any,
+> = {
+  resources: Readonly<
+    | [
+        CreatePermissionIntegrationRouterResourceOptions<
+          TResourceType1,
+          TResource1
+        >,
+      ]
+    | [
+        CreatePermissionIntegrationRouterResourceOptions<
+          TResourceType1,
+          TResource1
+        >,
+        CreatePermissionIntegrationRouterResourceOptions<
+          TResourceType2,
+          TResource2
+        >,
+      ]
+    | [
+        CreatePermissionIntegrationRouterResourceOptions<
+          TResourceType1,
+          TResource1
+        >,
+        CreatePermissionIntegrationRouterResourceOptions<
+          TResourceType2,
+          TResource2
+        >,
+        CreatePermissionIntegrationRouterResourceOptions<
+          TResourceType3,
+          TResource3
+        >,
+      ]
+  >;
 };
 
 /**
@@ -229,8 +259,8 @@ export type OptionResources<TResourceType extends string, TResource> = {
  * In case the `permissions` option is provided, the router also
  * provides a route that exposes permissions and routes of a plugin.
  *
- * In case an array of CreatePermissionIntegrationRouterResourceOptions is
- * provided, the routes can handle permissions for multiple resource types.
+ * In case resources is provided, the routes can handle permissions
+ * for multiple resource types.
  *
  * @remarks
  *
@@ -260,64 +290,6 @@ export type OptionResources<TResourceType extends string, TResource> = {
  *
  * @public
  */
-export function createPermissionIntegrationRouter<
-  TResourceType extends string,
-  TResource,
->(
-  options:
-    | CreatePermissionIntegrationRouterResourceOptions<TResourceType, TResource>
-    | {
-        resources: CreatePermissionIntegrationRouterResourceOptions<
-          TResourceType,
-          TResource
-        >;
-      },
-): express.Router;
-
-/**
- *
- * Create an express Router which provides a route that exposes
- * permissions and routes of a plugin.
- * @public
- */
-export function createPermissionIntegrationRouter(
-  options:
-    | { permissions: Array<Permission> }
-    | { resources: { permissions: Array<Permission> } },
-): express.Router;
-
-/**
- *
- * Create an express Router which provides an authorization route to allow
- * integration between the permission backend and other Backstage backend
- * plugins. Handles permissions for 2 resource types.
- * @public
- */
-export function createPermissionIntegrationRouter<
-  TResourceType1 extends string,
-  TResource1,
-  TResourceType2 extends string,
-  TResource2,
->(options: {
-  resources: [
-    CreatePermissionIntegrationRouterResourceOptions<
-      TResourceType1,
-      TResource1
-    >,
-    CreatePermissionIntegrationRouterResourceOptions<
-      TResourceType2,
-      TResource2
-    >,
-  ];
-}): express.Router;
-
-/**
- *
- * Create an express Router which provides an authorization route to allow
- * integration between the permission backend and other Backstage backend
- * plugins. Handles permissions for 3 resource types.
- * @public
- */
 export function createPermissionIntegrationRouter<
   TResourceType1 extends string,
   TResource1,
@@ -325,39 +297,23 @@ export function createPermissionIntegrationRouter<
   TResource2,
   TResourceType3 extends string,
   TResource3,
->(options: {
-  resources: [
-    CreatePermissionIntegrationRouterResourceOptions<
-      TResourceType1,
-      TResource1
-    >,
-    CreatePermissionIntegrationRouterResourceOptions<
-      TResourceType2,
-      TResource2
-    >,
-    CreatePermissionIntegrationRouterResourceOptions<
-      TResourceType3,
-      TResource3
-    >,
-  ];
-}): express.Router;
-
-/**
- * @public
- */
-export function createPermissionIntegrationRouter<
-  TResourceType extends string,
-  TResource,
 >(
   options:
     | { permissions: Array<Permission> }
-    | CreatePermissionIntegrationRouterResourceOptions<TResourceType, TResource>
-    | OptionResources<TResourceType, TResource>,
+    | CreatePermissionIntegrationRouterResourceOptions<
+        TResourceType1,
+        TResource1
+      >
+    | OptionResources<
+        TResourceType1,
+        TResource1,
+        TResourceType2,
+        TResource2,
+        TResourceType3,
+        TResource3
+      >,
 ): express.Router {
-  const optionsWithResources = options as OptionResources<
-    TResourceType,
-    TResource
-  >;
+  const optionsWithResources = options as OptionResources;
   const allOptions = [
     optionsWithResources.resources ? optionsWithResources.resources : options,
   ].flat();
@@ -365,8 +321,8 @@ export function createPermissionIntegrationRouter<
     option =>
       (
         option as CreatePermissionIntegrationRouterResourceOptions<
-          TResourceType,
-          TResource
+          TResourceType1,
+          TResource1
         >
       ).rules || [],
   );
@@ -381,16 +337,16 @@ export function createPermissionIntegrationRouter<
         option as
           | { permissions: Array<Permission> }
           | CreatePermissionIntegrationRouterResourceOptions<
-              TResourceType,
-              TResource
+              TResourceType1,
+              TResource1
             >,
       )
     ) {
       acc.push(
         (
           option as CreatePermissionIntegrationRouterResourceOptions<
-            TResourceType,
-            TResource
+            TResourceType1,
+            TResource1
           >
         ).resourceType,
       );
@@ -429,8 +385,8 @@ export function createPermissionIntegrationRouter<
       const getResourcesByResourceType: Record<
         string,
         CreatePermissionIntegrationRouterResourceOptions<
-          TResourceType,
-          TResource
+          TResourceType1,
+          TResource1
         >['getResources']
       > = {};
 
@@ -438,8 +394,8 @@ export function createPermissionIntegrationRouter<
         option = option as
           | { permissions: Array<Permission> }
           | CreatePermissionIntegrationRouterResourceOptions<
-              TResourceType,
-              TResource
+              TResourceType1,
+              TResource1
             >;
         if (isCreatePermissionIntegrationRouterResourceOptions(option)) {
           ruleMapByResourceType[option.resourceType] = createGetRule(