diff --git a/test/__snapshots__/index.spec.ts.snap b/test/__snapshots__/index.spec.ts.snap
index bdd0ef67..bb00203d 100644
--- a/test/__snapshots__/index.spec.ts.snap
+++ b/test/__snapshots__/index.spec.ts.snap
@@ -210,11 +210,11 @@ export type OpenAPIConfig = {
     VERSION: string;
     WITH_CREDENTIALS: boolean;
     CREDENTIALS: 'include' | 'omit' | 'same-origin';
-    TOKEN?: string | Resolver<string>;
-    USERNAME?: string | Resolver<string>;
-    PASSWORD?: string | Resolver<string>;
-    HEADERS?: Headers | Resolver<Headers>;
-    ENCODE_PATH?: (path: string) => string;
+    TOKEN?: string | Resolver<string> | undefined;
+    USERNAME?: string | Resolver<string> | undefined;
+    PASSWORD?: string | Resolver<string> | undefined;
+    HEADERS?: Headers | Resolver<Headers> | undefined;
+    ENCODE_PATH?: ((path: string) => string) | undefined;
 };
 
 export const OpenAPI: OpenAPIConfig = {
@@ -3317,11 +3317,11 @@ export type OpenAPIConfig = {
     VERSION: string;
     WITH_CREDENTIALS: boolean;
     CREDENTIALS: 'include' | 'omit' | 'same-origin';
-    TOKEN?: string | Resolver<string>;
-    USERNAME?: string | Resolver<string>;
-    PASSWORD?: string | Resolver<string>;
-    HEADERS?: Headers | Resolver<Headers>;
-    ENCODE_PATH?: (path: string) => string;
+    TOKEN?: string | Resolver<string> | undefined;
+    USERNAME?: string | Resolver<string> | undefined;
+    PASSWORD?: string | Resolver<string> | undefined;
+    HEADERS?: Headers | Resolver<Headers> | undefined;
+    ENCODE_PATH?: ((path: string) => string) | undefined;
 };
 
 export const OpenAPI: OpenAPIConfig = {
diff --git a/test/e2e/client.angular.spec.ts b/test/e2e/client.angular.spec.ts
index ec77b5ee..54dd5bc8 100644
--- a/test/e2e/client.angular.spec.ts
+++ b/test/e2e/client.angular.spec.ts
@@ -143,7 +143,8 @@ describe('client.angular', () => {
         expect(error).toBe(
             JSON.stringify({
                 name: 'ApiError',
-                message: 'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
+                message:
+                    'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
                 url: 'http://localhost:3000/base/api/v1.0/error?status=409',
                 status: 409,
                 statusText: 'Conflict',
diff --git a/test/e2e/client.axios.spec.ts b/test/e2e/client.axios.spec.ts
index c3b28013..a0ba5475 100644
--- a/test/e2e/client.axios.spec.ts
+++ b/test/e2e/client.axios.spec.ts
@@ -136,7 +136,8 @@ describe('client.axios', () => {
         expect(error).toBe(
             JSON.stringify({
                 name: 'ApiError',
-                message: 'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
+                message:
+                    'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
                 url: 'http://localhost:3000/base/api/v1.0/error?status=409',
                 status: 409,
                 statusText: 'Conflict',
diff --git a/test/e2e/client.babel.spec.ts b/test/e2e/client.babel.spec.ts
index 9a2671df..b8814bdd 100644
--- a/test/e2e/client.babel.spec.ts
+++ b/test/e2e/client.babel.spec.ts
@@ -161,7 +161,8 @@ describe('client.babel', () => {
         expect(error).toBe(
             JSON.stringify({
                 name: 'ApiError',
-                message: 'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
+                message:
+                    'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
                 url: 'http://localhost:3000/base/api/v1.0/error?status=409',
                 status: 409,
                 statusText: 'Conflict',
diff --git a/test/e2e/client.fetch.spec.ts b/test/e2e/client.fetch.spec.ts
index 54fd9ef2..ce236268 100644
--- a/test/e2e/client.fetch.spec.ts
+++ b/test/e2e/client.fetch.spec.ts
@@ -156,7 +156,8 @@ describe('client.fetch', () => {
         expect(error).toBe(
             JSON.stringify({
                 name: 'ApiError',
-                message: 'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
+                message:
+                    'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
                 url: 'http://localhost:3000/base/api/v1.0/error?status=409',
                 status: 409,
                 statusText: 'Conflict',
diff --git a/test/e2e/client.node.spec.ts b/test/e2e/client.node.spec.ts
index 55bcee73..0d915919 100644
--- a/test/e2e/client.node.spec.ts
+++ b/test/e2e/client.node.spec.ts
@@ -136,7 +136,8 @@ describe('client.node', () => {
         expect(error).toBe(
             JSON.stringify({
                 name: 'ApiError',
-                message: 'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
+                message:
+                    'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
                 url: 'http://localhost:3000/base/api/v1.0/error?status=409',
                 status: 409,
                 statusText: 'Conflict',
diff --git a/test/e2e/client.xhr.spec.ts b/test/e2e/client.xhr.spec.ts
index 0b8f3e0e..be1334b7 100644
--- a/test/e2e/client.xhr.spec.ts
+++ b/test/e2e/client.xhr.spec.ts
@@ -155,7 +155,8 @@ describe('client.xhr', () => {
         expect(error).toBe(
             JSON.stringify({
                 name: 'ApiError',
-                message: 'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
+                message:
+                    'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
                 url: 'http://localhost:3000/base/api/v1.0/error?status=409',
                 status: 409,
                 statusText: 'Conflict',
diff --git a/test/e2e/v3.angular.spec.ts b/test/e2e/v3.angular.spec.ts
index 8b2faca7..85e87b58 100644
--- a/test/e2e/v3.angular.spec.ts
+++ b/test/e2e/v3.angular.spec.ts
@@ -144,7 +144,8 @@ describe('v3.angular', () => {
         expect(error).toBe(
             JSON.stringify({
                 name: 'ApiError',
-                message: 'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
+                message:
+                    'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
                 url: 'http://localhost:3000/base/api/v1.0/error?status=409',
                 status: 409,
                 statusText: 'Conflict',
diff --git a/test/e2e/v3.axios.spec.ts b/test/e2e/v3.axios.spec.ts
index c6e44e6a..56b21be3 100644
--- a/test/e2e/v3.axios.spec.ts
+++ b/test/e2e/v3.axios.spec.ts
@@ -127,7 +127,8 @@ describe('v3.axios', () => {
         expect(error).toBe(
             JSON.stringify({
                 name: 'ApiError',
-                message: 'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
+                message:
+                    'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
                 url: 'http://localhost:3000/base/api/v1.0/error?status=409',
                 status: 409,
                 statusText: 'Conflict',
diff --git a/test/e2e/v3.babel.spec.ts b/test/e2e/v3.babel.spec.ts
index c747c7e3..6f54f306 100644
--- a/test/e2e/v3.babel.spec.ts
+++ b/test/e2e/v3.babel.spec.ts
@@ -153,7 +153,8 @@ describe('v3.babel', () => {
         expect(error).toBe(
             JSON.stringify({
                 name: 'ApiError',
-                message: 'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
+                message:
+                    'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
                 url: 'http://localhost:3000/base/api/v1.0/error?status=409',
                 status: 409,
                 statusText: 'Conflict',
diff --git a/test/e2e/v3.fetch.spec.ts b/test/e2e/v3.fetch.spec.ts
index e1e721c9..f37c23a9 100644
--- a/test/e2e/v3.fetch.spec.ts
+++ b/test/e2e/v3.fetch.spec.ts
@@ -147,7 +147,8 @@ describe('v3.fetch', () => {
         expect(error).toBe(
             JSON.stringify({
                 name: 'ApiError',
-                message: 'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
+                message:
+                    'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
                 url: 'http://localhost:3000/base/api/v1.0/error?status=409',
                 status: 409,
                 statusText: 'Conflict',
diff --git a/test/e2e/v3.node.spec.ts b/test/e2e/v3.node.spec.ts
index 2adf0259..6d6a484c 100644
--- a/test/e2e/v3.node.spec.ts
+++ b/test/e2e/v3.node.spec.ts
@@ -127,7 +127,8 @@ describe('v3.node', () => {
         expect(error).toBe(
             JSON.stringify({
                 name: 'ApiError',
-                message: 'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
+                message:
+                    'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
                 url: 'http://localhost:3000/base/api/v1.0/error?status=409',
                 status: 409,
                 statusText: 'Conflict',
diff --git a/test/e2e/v3.xhr.spec.ts b/test/e2e/v3.xhr.spec.ts
index e2ad2537..80930148 100644
--- a/test/e2e/v3.xhr.spec.ts
+++ b/test/e2e/v3.xhr.spec.ts
@@ -146,7 +146,8 @@ describe('v3.xhr', () => {
         expect(error).toBe(
             JSON.stringify({
                 name: 'ApiError',
-                message: 'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
+                message:
+                    'Generic Error: status: 409; status text: Conflict; body: {\n  "status": 409,\n  "message": "hello world"\n}',
                 url: 'http://localhost:3000/base/api/v1.0/error?status=409',
                 status: 409,
                 statusText: 'Conflict',