diff --git a/modules/openapi-generator/src/main/resources/swift5/libraries/urlsession/URLSessionImplementations.mustache b/modules/openapi-generator/src/main/resources/swift5/libraries/urlsession/URLSessionImplementations.mustache
index b544298de362..a369e6f0eea5 100644
--- a/modules/openapi-generator/src/main/resources/swift5/libraries/urlsession/URLSessionImplementations.mustache
+++ b/modules/openapi-generator/src/main/resources/swift5/libraries/urlsession/URLSessionImplementations.mustache
@@ -92,10 +92,6 @@ private var credentialStore = SynchronizedDictionary<Int, URLCredential>()
 
         originalRequest.httpMethod = method.rawValue
 
-        headers.forEach { key, value in
-            originalRequest.setValue(value, forHTTPHeaderField: key)
-        }
-
         buildHeaders().forEach { key, value in
             originalRequest.setValue(value, forHTTPHeaderField: key)
         }
@@ -218,10 +214,10 @@ private var credentialStore = SynchronizedDictionary<Int, URLCredential>()
 
     {{#nonPublicApi}}internal{{/nonPublicApi}}{{^nonPublicApi}}open{{/nonPublicApi}} func buildHeaders() -> [String: String] {
         var httpHeaders: [String: String] = [:]
-        for (key, value) in headers {
+        for (key, value) in {{projectName}}API.customHeaders {
             httpHeaders[key] = value
         }
-        for (key, value) in {{projectName}}API.customHeaders {
+        for (key, value) in headers {
             httpHeaders[key] = value
         }
         return httpHeaders
diff --git a/samples/client/petstore/swift5/asyncAwaitLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift b/samples/client/petstore/swift5/asyncAwaitLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
index 635c69cd6a8a..da9dca29ac46 100644
--- a/samples/client/petstore/swift5/asyncAwaitLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
+++ b/samples/client/petstore/swift5/asyncAwaitLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
@@ -92,10 +92,6 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
         originalRequest.httpMethod = method.rawValue
 
-        headers.forEach { key, value in
-            originalRequest.setValue(value, forHTTPHeaderField: key)
-        }
-
         buildHeaders().forEach { key, value in
             originalRequest.setValue(value, forHTTPHeaderField: key)
         }
@@ -218,10 +214,10 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
     open func buildHeaders() -> [String: String] {
         var httpHeaders: [String: String] = [:]
-        for (key, value) in headers {
+        for (key, value) in PetstoreClientAPI.customHeaders {
             httpHeaders[key] = value
         }
-        for (key, value) in PetstoreClientAPI.customHeaders {
+        for (key, value) in headers {
             httpHeaders[key] = value
         }
         return httpHeaders
diff --git a/samples/client/petstore/swift5/combineLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift b/samples/client/petstore/swift5/combineLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
index 635c69cd6a8a..da9dca29ac46 100644
--- a/samples/client/petstore/swift5/combineLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
+++ b/samples/client/petstore/swift5/combineLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
@@ -92,10 +92,6 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
         originalRequest.httpMethod = method.rawValue
 
-        headers.forEach { key, value in
-            originalRequest.setValue(value, forHTTPHeaderField: key)
-        }
-
         buildHeaders().forEach { key, value in
             originalRequest.setValue(value, forHTTPHeaderField: key)
         }
@@ -218,10 +214,10 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
     open func buildHeaders() -> [String: String] {
         var httpHeaders: [String: String] = [:]
-        for (key, value) in headers {
+        for (key, value) in PetstoreClientAPI.customHeaders {
             httpHeaders[key] = value
         }
-        for (key, value) in PetstoreClientAPI.customHeaders {
+        for (key, value) in headers {
             httpHeaders[key] = value
         }
         return httpHeaders
diff --git a/samples/client/petstore/swift5/default/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift b/samples/client/petstore/swift5/default/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
index 635c69cd6a8a..da9dca29ac46 100644
--- a/samples/client/petstore/swift5/default/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
+++ b/samples/client/petstore/swift5/default/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
@@ -92,10 +92,6 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
         originalRequest.httpMethod = method.rawValue
 
-        headers.forEach { key, value in
-            originalRequest.setValue(value, forHTTPHeaderField: key)
-        }
-
         buildHeaders().forEach { key, value in
             originalRequest.setValue(value, forHTTPHeaderField: key)
         }
@@ -218,10 +214,10 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
     open func buildHeaders() -> [String: String] {
         var httpHeaders: [String: String] = [:]
-        for (key, value) in headers {
+        for (key, value) in PetstoreClientAPI.customHeaders {
             httpHeaders[key] = value
         }
-        for (key, value) in PetstoreClientAPI.customHeaders {
+        for (key, value) in headers {
             httpHeaders[key] = value
         }
         return httpHeaders
diff --git a/samples/client/petstore/swift5/deprecated/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift b/samples/client/petstore/swift5/deprecated/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
index 635c69cd6a8a..da9dca29ac46 100644
--- a/samples/client/petstore/swift5/deprecated/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
+++ b/samples/client/petstore/swift5/deprecated/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
@@ -92,10 +92,6 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
         originalRequest.httpMethod = method.rawValue
 
-        headers.forEach { key, value in
-            originalRequest.setValue(value, forHTTPHeaderField: key)
-        }
-
         buildHeaders().forEach { key, value in
             originalRequest.setValue(value, forHTTPHeaderField: key)
         }
@@ -218,10 +214,10 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
     open func buildHeaders() -> [String: String] {
         var httpHeaders: [String: String] = [:]
-        for (key, value) in headers {
+        for (key, value) in PetstoreClientAPI.customHeaders {
             httpHeaders[key] = value
         }
-        for (key, value) in PetstoreClientAPI.customHeaders {
+        for (key, value) in headers {
             httpHeaders[key] = value
         }
         return httpHeaders
diff --git a/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift b/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
index 635c69cd6a8a..da9dca29ac46 100644
--- a/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
+++ b/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
@@ -92,10 +92,6 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
         originalRequest.httpMethod = method.rawValue
 
-        headers.forEach { key, value in
-            originalRequest.setValue(value, forHTTPHeaderField: key)
-        }
-
         buildHeaders().forEach { key, value in
             originalRequest.setValue(value, forHTTPHeaderField: key)
         }
@@ -218,10 +214,10 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
     open func buildHeaders() -> [String: String] {
         var httpHeaders: [String: String] = [:]
-        for (key, value) in headers {
+        for (key, value) in PetstoreClientAPI.customHeaders {
             httpHeaders[key] = value
         }
-        for (key, value) in PetstoreClientAPI.customHeaders {
+        for (key, value) in headers {
             httpHeaders[key] = value
         }
         return httpHeaders
diff --git a/samples/client/petstore/swift5/nonPublicApi/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift b/samples/client/petstore/swift5/nonPublicApi/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
index e8f1e1ec614a..86926821e793 100644
--- a/samples/client/petstore/swift5/nonPublicApi/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
+++ b/samples/client/petstore/swift5/nonPublicApi/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
@@ -92,10 +92,6 @@ internal class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
         originalRequest.httpMethod = method.rawValue
 
-        headers.forEach { key, value in
-            originalRequest.setValue(value, forHTTPHeaderField: key)
-        }
-
         buildHeaders().forEach { key, value in
             originalRequest.setValue(value, forHTTPHeaderField: key)
         }
@@ -218,10 +214,10 @@ internal class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
     internal func buildHeaders() -> [String: String] {
         var httpHeaders: [String: String] = [:]
-        for (key, value) in headers {
+        for (key, value) in PetstoreClientAPI.customHeaders {
             httpHeaders[key] = value
         }
-        for (key, value) in PetstoreClientAPI.customHeaders {
+        for (key, value) in headers {
             httpHeaders[key] = value
         }
         return httpHeaders
diff --git a/samples/client/petstore/swift5/objcCompatible/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift b/samples/client/petstore/swift5/objcCompatible/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
index 635c69cd6a8a..da9dca29ac46 100644
--- a/samples/client/petstore/swift5/objcCompatible/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
+++ b/samples/client/petstore/swift5/objcCompatible/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
@@ -92,10 +92,6 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
         originalRequest.httpMethod = method.rawValue
 
-        headers.forEach { key, value in
-            originalRequest.setValue(value, forHTTPHeaderField: key)
-        }
-
         buildHeaders().forEach { key, value in
             originalRequest.setValue(value, forHTTPHeaderField: key)
         }
@@ -218,10 +214,10 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
     open func buildHeaders() -> [String: String] {
         var httpHeaders: [String: String] = [:]
-        for (key, value) in headers {
+        for (key, value) in PetstoreClientAPI.customHeaders {
             httpHeaders[key] = value
         }
-        for (key, value) in PetstoreClientAPI.customHeaders {
+        for (key, value) in headers {
             httpHeaders[key] = value
         }
         return httpHeaders
diff --git a/samples/client/petstore/swift5/oneOf/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift b/samples/client/petstore/swift5/oneOf/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
index 635c69cd6a8a..da9dca29ac46 100644
--- a/samples/client/petstore/swift5/oneOf/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
+++ b/samples/client/petstore/swift5/oneOf/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
@@ -92,10 +92,6 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
         originalRequest.httpMethod = method.rawValue
 
-        headers.forEach { key, value in
-            originalRequest.setValue(value, forHTTPHeaderField: key)
-        }
-
         buildHeaders().forEach { key, value in
             originalRequest.setValue(value, forHTTPHeaderField: key)
         }
@@ -218,10 +214,10 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
     open func buildHeaders() -> [String: String] {
         var httpHeaders: [String: String] = [:]
-        for (key, value) in headers {
+        for (key, value) in PetstoreClientAPI.customHeaders {
             httpHeaders[key] = value
         }
-        for (key, value) in PetstoreClientAPI.customHeaders {
+        for (key, value) in headers {
             httpHeaders[key] = value
         }
         return httpHeaders
diff --git a/samples/client/petstore/swift5/promisekitLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift b/samples/client/petstore/swift5/promisekitLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
index 635c69cd6a8a..da9dca29ac46 100644
--- a/samples/client/petstore/swift5/promisekitLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
+++ b/samples/client/petstore/swift5/promisekitLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
@@ -92,10 +92,6 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
         originalRequest.httpMethod = method.rawValue
 
-        headers.forEach { key, value in
-            originalRequest.setValue(value, forHTTPHeaderField: key)
-        }
-
         buildHeaders().forEach { key, value in
             originalRequest.setValue(value, forHTTPHeaderField: key)
         }
@@ -218,10 +214,10 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
     open func buildHeaders() -> [String: String] {
         var httpHeaders: [String: String] = [:]
-        for (key, value) in headers {
+        for (key, value) in PetstoreClientAPI.customHeaders {
             httpHeaders[key] = value
         }
-        for (key, value) in PetstoreClientAPI.customHeaders {
+        for (key, value) in headers {
             httpHeaders[key] = value
         }
         return httpHeaders
diff --git a/samples/client/petstore/swift5/readonlyProperties/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift b/samples/client/petstore/swift5/readonlyProperties/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
index 635c69cd6a8a..da9dca29ac46 100644
--- a/samples/client/petstore/swift5/readonlyProperties/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
+++ b/samples/client/petstore/swift5/readonlyProperties/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
@@ -92,10 +92,6 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
         originalRequest.httpMethod = method.rawValue
 
-        headers.forEach { key, value in
-            originalRequest.setValue(value, forHTTPHeaderField: key)
-        }
-
         buildHeaders().forEach { key, value in
             originalRequest.setValue(value, forHTTPHeaderField: key)
         }
@@ -218,10 +214,10 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
     open func buildHeaders() -> [String: String] {
         var httpHeaders: [String: String] = [:]
-        for (key, value) in headers {
+        for (key, value) in PetstoreClientAPI.customHeaders {
             httpHeaders[key] = value
         }
-        for (key, value) in PetstoreClientAPI.customHeaders {
+        for (key, value) in headers {
             httpHeaders[key] = value
         }
         return httpHeaders
diff --git a/samples/client/petstore/swift5/resultLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift b/samples/client/petstore/swift5/resultLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
index 635c69cd6a8a..da9dca29ac46 100644
--- a/samples/client/petstore/swift5/resultLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
+++ b/samples/client/petstore/swift5/resultLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
@@ -92,10 +92,6 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
         originalRequest.httpMethod = method.rawValue
 
-        headers.forEach { key, value in
-            originalRequest.setValue(value, forHTTPHeaderField: key)
-        }
-
         buildHeaders().forEach { key, value in
             originalRequest.setValue(value, forHTTPHeaderField: key)
         }
@@ -218,10 +214,10 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
     open func buildHeaders() -> [String: String] {
         var httpHeaders: [String: String] = [:]
-        for (key, value) in headers {
+        for (key, value) in PetstoreClientAPI.customHeaders {
             httpHeaders[key] = value
         }
-        for (key, value) in PetstoreClientAPI.customHeaders {
+        for (key, value) in headers {
             httpHeaders[key] = value
         }
         return httpHeaders
diff --git a/samples/client/petstore/swift5/rxswiftLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift b/samples/client/petstore/swift5/rxswiftLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
index 635c69cd6a8a..da9dca29ac46 100644
--- a/samples/client/petstore/swift5/rxswiftLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
+++ b/samples/client/petstore/swift5/rxswiftLibrary/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
@@ -92,10 +92,6 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
         originalRequest.httpMethod = method.rawValue
 
-        headers.forEach { key, value in
-            originalRequest.setValue(value, forHTTPHeaderField: key)
-        }
-
         buildHeaders().forEach { key, value in
             originalRequest.setValue(value, forHTTPHeaderField: key)
         }
@@ -218,10 +214,10 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
     open func buildHeaders() -> [String: String] {
         var httpHeaders: [String: String] = [:]
-        for (key, value) in headers {
+        for (key, value) in PetstoreClientAPI.customHeaders {
             httpHeaders[key] = value
         }
-        for (key, value) in PetstoreClientAPI.customHeaders {
+        for (key, value) in headers {
             httpHeaders[key] = value
         }
         return httpHeaders
diff --git a/samples/client/petstore/swift5/urlsessionLibrary/Sources/PetstoreClient/URLSessionImplementations.swift b/samples/client/petstore/swift5/urlsessionLibrary/Sources/PetstoreClient/URLSessionImplementations.swift
index 635c69cd6a8a..da9dca29ac46 100644
--- a/samples/client/petstore/swift5/urlsessionLibrary/Sources/PetstoreClient/URLSessionImplementations.swift
+++ b/samples/client/petstore/swift5/urlsessionLibrary/Sources/PetstoreClient/URLSessionImplementations.swift
@@ -92,10 +92,6 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
         originalRequest.httpMethod = method.rawValue
 
-        headers.forEach { key, value in
-            originalRequest.setValue(value, forHTTPHeaderField: key)
-        }
-
         buildHeaders().forEach { key, value in
             originalRequest.setValue(value, forHTTPHeaderField: key)
         }
@@ -218,10 +214,10 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
     open func buildHeaders() -> [String: String] {
         var httpHeaders: [String: String] = [:]
-        for (key, value) in headers {
+        for (key, value) in PetstoreClientAPI.customHeaders {
             httpHeaders[key] = value
         }
-        for (key, value) in PetstoreClientAPI.customHeaders {
+        for (key, value) in headers {
             httpHeaders[key] = value
         }
         return httpHeaders
diff --git a/samples/client/petstore/swift5/x-swift-hashable/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift b/samples/client/petstore/swift5/x-swift-hashable/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
index 635c69cd6a8a..da9dca29ac46 100644
--- a/samples/client/petstore/swift5/x-swift-hashable/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
+++ b/samples/client/petstore/swift5/x-swift-hashable/PetstoreClient/Classes/OpenAPIs/URLSessionImplementations.swift
@@ -92,10 +92,6 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
         originalRequest.httpMethod = method.rawValue
 
-        headers.forEach { key, value in
-            originalRequest.setValue(value, forHTTPHeaderField: key)
-        }
-
         buildHeaders().forEach { key, value in
             originalRequest.setValue(value, forHTTPHeaderField: key)
         }
@@ -218,10 +214,10 @@ open class URLSessionRequestBuilder<T>: RequestBuilder<T> {
 
     open func buildHeaders() -> [String: String] {
         var httpHeaders: [String: String] = [:]
-        for (key, value) in headers {
+        for (key, value) in PetstoreClientAPI.customHeaders {
             httpHeaders[key] = value
         }
-        for (key, value) in PetstoreClientAPI.customHeaders {
+        for (key, value) in headers {
             httpHeaders[key] = value
         }
         return httpHeaders