diff --git a/modules/openapi-generator/src/main/resources/swift5/APIs.mustache b/modules/openapi-generator/src/main/resources/swift5/APIs.mustache
index e670d7d5c8c..76d1a9fae24 100644
--- a/modules/openapi-generator/src/main/resources/swift5/APIs.mustache
+++ b/modules/openapi-generator/src/main/resources/swift5/APIs.mustache
@@ -45,6 +45,7 @@ import Vapor
         self.requiresAuthentication = requiresAuthentication
 
         addHeaders({{projectName}}API.customHeaders)
+        addCredential()
     }
 
     {{#nonPublicApi}}internal{{/nonPublicApi}}{{^nonPublicApi}}open{{/nonPublicApi}} func addHeaders(_ aHeaders: [String: String]) {
@@ -92,9 +93,8 @@ import Vapor
         return self
     }
 
-    {{#nonPublicApi}}internal{{/nonPublicApi}}{{^nonPublicApi}}open{{/nonPublicApi}} func addCredential() -> Self {
+    {{#nonPublicApi}}internal{{/nonPublicApi}}{{^nonPublicApi}}open{{/nonPublicApi}} func addCredential() {
         credential = {{projectName}}API.credential
-        return self
     }
 }
 
diff --git a/samples/client/petstore/swift5/alamofireLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift b/samples/client/petstore/swift5/alamofireLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift
index 5c231fce667..81948617ef6 100644
--- a/samples/client/petstore/swift5/alamofireLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift
+++ b/samples/client/petstore/swift5/alamofireLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift
@@ -36,6 +36,7 @@ open class RequestBuilder<T> {
         self.requiresAuthentication = requiresAuthentication
 
         addHeaders(PetstoreClientAPI.customHeaders)
+        addCredential()
     }
 
     open func addHeaders(_ aHeaders: [String: String]) {
@@ -56,9 +57,8 @@ open class RequestBuilder<T> {
         return self
     }
 
-    open func addCredential() -> Self {
+    open func addCredential() {
         credential = PetstoreClientAPI.credential
-        return self
     }
 }
 
diff --git a/samples/client/petstore/swift5/asyncAwaitLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift b/samples/client/petstore/swift5/asyncAwaitLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift
index b9d23cc0fda..9e5d3c0a772 100644
--- a/samples/client/petstore/swift5/asyncAwaitLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift
+++ b/samples/client/petstore/swift5/asyncAwaitLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift
@@ -36,6 +36,7 @@ open class RequestBuilder<T> {
         self.requiresAuthentication = requiresAuthentication
 
         addHeaders(PetstoreClientAPI.customHeaders)
+        addCredential()
     }
 
     open func addHeaders(_ aHeaders: [String: String]) {
@@ -81,9 +82,8 @@ open class RequestBuilder<T> {
         return self
     }
 
-    open func addCredential() -> Self {
+    open func addCredential() {
         credential = PetstoreClientAPI.credential
-        return self
     }
 }
 
diff --git a/samples/client/petstore/swift5/combineLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift b/samples/client/petstore/swift5/combineLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift
index 67757f368a9..3ad11a871d5 100644
--- a/samples/client/petstore/swift5/combineLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift
+++ b/samples/client/petstore/swift5/combineLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift
@@ -36,6 +36,7 @@ open class RequestBuilder<T> {
         self.requiresAuthentication = requiresAuthentication
 
         addHeaders(PetstoreClientAPI.customHeaders)
+        addCredential()
     }
 
     open func addHeaders(_ aHeaders: [String: String]) {
@@ -56,9 +57,8 @@ open class RequestBuilder<T> {
         return self
     }
 
-    open func addCredential() -> Self {
+    open func addCredential() {
         credential = PetstoreClientAPI.credential
-        return self
     }
 }
 
diff --git a/samples/client/petstore/swift5/default/PetstoreClient/Classes/OpenAPIs/APIs.swift b/samples/client/petstore/swift5/default/PetstoreClient/Classes/OpenAPIs/APIs.swift
index 67757f368a9..3ad11a871d5 100644
--- a/samples/client/petstore/swift5/default/PetstoreClient/Classes/OpenAPIs/APIs.swift
+++ b/samples/client/petstore/swift5/default/PetstoreClient/Classes/OpenAPIs/APIs.swift
@@ -36,6 +36,7 @@ open class RequestBuilder<T> {
         self.requiresAuthentication = requiresAuthentication
 
         addHeaders(PetstoreClientAPI.customHeaders)
+        addCredential()
     }
 
     open func addHeaders(_ aHeaders: [String: String]) {
@@ -56,9 +57,8 @@ open class RequestBuilder<T> {
         return self
     }
 
-    open func addCredential() -> Self {
+    open func addCredential() {
         credential = PetstoreClientAPI.credential
-        return self
     }
 }
 
diff --git a/samples/client/petstore/swift5/objcCompatible/PetstoreClient/Classes/OpenAPIs/APIs.swift b/samples/client/petstore/swift5/objcCompatible/PetstoreClient/Classes/OpenAPIs/APIs.swift
index 67757f368a9..3ad11a871d5 100644
--- a/samples/client/petstore/swift5/objcCompatible/PetstoreClient/Classes/OpenAPIs/APIs.swift
+++ b/samples/client/petstore/swift5/objcCompatible/PetstoreClient/Classes/OpenAPIs/APIs.swift
@@ -36,6 +36,7 @@ open class RequestBuilder<T> {
         self.requiresAuthentication = requiresAuthentication
 
         addHeaders(PetstoreClientAPI.customHeaders)
+        addCredential()
     }
 
     open func addHeaders(_ aHeaders: [String: String]) {
@@ -56,9 +57,8 @@ open class RequestBuilder<T> {
         return self
     }
 
-    open func addCredential() -> Self {
+    open func addCredential() {
         credential = PetstoreClientAPI.credential
-        return self
     }
 }
 
diff --git a/samples/client/petstore/swift5/oneOf/PetstoreClient/Classes/OpenAPIs/APIs.swift b/samples/client/petstore/swift5/oneOf/PetstoreClient/Classes/OpenAPIs/APIs.swift
index dfe73eb99ac..ac0a6317e6e 100644
--- a/samples/client/petstore/swift5/oneOf/PetstoreClient/Classes/OpenAPIs/APIs.swift
+++ b/samples/client/petstore/swift5/oneOf/PetstoreClient/Classes/OpenAPIs/APIs.swift
@@ -36,6 +36,7 @@ open class RequestBuilder<T> {
         self.requiresAuthentication = requiresAuthentication
 
         addHeaders(PetstoreClientAPI.customHeaders)
+        addCredential()
     }
 
     open func addHeaders(_ aHeaders: [String: String]) {
@@ -56,9 +57,8 @@ open class RequestBuilder<T> {
         return self
     }
 
-    open func addCredential() -> Self {
+    open func addCredential() {
         credential = PetstoreClientAPI.credential
-        return self
     }
 }
 
diff --git a/samples/client/petstore/swift5/promisekitLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift b/samples/client/petstore/swift5/promisekitLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift
index 67757f368a9..3ad11a871d5 100644
--- a/samples/client/petstore/swift5/promisekitLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift
+++ b/samples/client/petstore/swift5/promisekitLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift
@@ -36,6 +36,7 @@ open class RequestBuilder<T> {
         self.requiresAuthentication = requiresAuthentication
 
         addHeaders(PetstoreClientAPI.customHeaders)
+        addCredential()
     }
 
     open func addHeaders(_ aHeaders: [String: String]) {
@@ -56,9 +57,8 @@ open class RequestBuilder<T> {
         return self
     }
 
-    open func addCredential() -> Self {
+    open func addCredential() {
         credential = PetstoreClientAPI.credential
-        return self
     }
 }
 
diff --git a/samples/client/petstore/swift5/resultLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift b/samples/client/petstore/swift5/resultLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift
index 5f9e2d9dfb9..774626d6fa9 100644
--- a/samples/client/petstore/swift5/resultLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift
+++ b/samples/client/petstore/swift5/resultLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift
@@ -36,6 +36,7 @@ internal class RequestBuilder<T> {
         self.requiresAuthentication = requiresAuthentication
 
         addHeaders(PetstoreClientAPI.customHeaders)
+        addCredential()
     }
 
     internal func addHeaders(_ aHeaders: [String: String]) {
@@ -56,9 +57,8 @@ internal class RequestBuilder<T> {
         return self
     }
 
-    internal func addCredential() -> Self {
+    internal func addCredential() {
         credential = PetstoreClientAPI.credential
-        return self
     }
 }
 
diff --git a/samples/client/petstore/swift5/rxswiftLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift b/samples/client/petstore/swift5/rxswiftLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift
index 67757f368a9..3ad11a871d5 100644
--- a/samples/client/petstore/swift5/rxswiftLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift
+++ b/samples/client/petstore/swift5/rxswiftLibrary/PetstoreClient/Classes/OpenAPIs/APIs.swift
@@ -36,6 +36,7 @@ open class RequestBuilder<T> {
         self.requiresAuthentication = requiresAuthentication
 
         addHeaders(PetstoreClientAPI.customHeaders)
+        addCredential()
     }
 
     open func addHeaders(_ aHeaders: [String: String]) {
@@ -56,9 +57,8 @@ open class RequestBuilder<T> {
         return self
     }
 
-    open func addCredential() -> Self {
+    open func addCredential() {
         credential = PetstoreClientAPI.credential
-        return self
     }
 }
 
diff --git a/samples/client/petstore/swift5/urlsessionLibrary/Sources/PetstoreClient/APIs.swift b/samples/client/petstore/swift5/urlsessionLibrary/Sources/PetstoreClient/APIs.swift
index 67757f368a9..3ad11a871d5 100644
--- a/samples/client/petstore/swift5/urlsessionLibrary/Sources/PetstoreClient/APIs.swift
+++ b/samples/client/petstore/swift5/urlsessionLibrary/Sources/PetstoreClient/APIs.swift
@@ -36,6 +36,7 @@ open class RequestBuilder<T> {
         self.requiresAuthentication = requiresAuthentication
 
         addHeaders(PetstoreClientAPI.customHeaders)
+        addCredential()
     }
 
     open func addHeaders(_ aHeaders: [String: String]) {
@@ -56,9 +57,8 @@ open class RequestBuilder<T> {
         return self
     }
 
-    open func addCredential() -> Self {
+    open func addCredential() {
         credential = PetstoreClientAPI.credential
-        return self
     }
 }
 
diff --git a/samples/client/petstore/swift5/validation/PetstoreClient/Classes/OpenAPIs/APIs.swift b/samples/client/petstore/swift5/validation/PetstoreClient/Classes/OpenAPIs/APIs.swift
index dfe73eb99ac..ac0a6317e6e 100644
--- a/samples/client/petstore/swift5/validation/PetstoreClient/Classes/OpenAPIs/APIs.swift
+++ b/samples/client/petstore/swift5/validation/PetstoreClient/Classes/OpenAPIs/APIs.swift
@@ -36,6 +36,7 @@ open class RequestBuilder<T> {
         self.requiresAuthentication = requiresAuthentication
 
         addHeaders(PetstoreClientAPI.customHeaders)
+        addCredential()
     }
 
     open func addHeaders(_ aHeaders: [String: String]) {
@@ -56,9 +57,8 @@ open class RequestBuilder<T> {
         return self
     }
 
-    open func addCredential() -> Self {
+    open func addCredential() {
         credential = PetstoreClientAPI.credential
-        return self
     }
 }