diff --git a/lib/Api/HookApi.php b/lib/Api/HookApi.php
index dda8ea0..de716de 100644
--- a/lib/Api/HookApi.php
+++ b/lib/Api/HookApi.php
@@ -404,10 +404,10 @@ public function getHookConfigsRequest()
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -674,10 +674,10 @@ public function getHooksRequest($party_id)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -895,10 +895,10 @@ public function removeHookConfigRequest($hook_id)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1165,10 +1165,10 @@ public function sendHookPingRequest($party_id)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1429,10 +1429,10 @@ public function setHookConfigRequest($hook)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1716,10 +1716,10 @@ public function subscribeRequest($party_id, $hook)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1960,10 +1960,10 @@ public function unSubscribeRequest($party_id, $hook_id)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
diff --git a/lib/Api/MeApi.php b/lib/Api/MeApi.php
index b96e9ff..c5fffcf 100644
--- a/lib/Api/MeApi.php
+++ b/lib/Api/MeApi.php
@@ -403,10 +403,10 @@ public function getUserRequest()
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -650,10 +650,10 @@ public function getUserPartyRequest()
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
diff --git a/lib/Api/PeppolApi.php b/lib/Api/PeppolApi.php
index ac19b44..c844038 100644
--- a/lib/Api/PeppolApi.php
+++ b/lib/Api/PeppolApi.php
@@ -485,10 +485,10 @@ public function getDeliveryOptionsRequest($party_ids, $preferred_document_type_i
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -729,10 +729,10 @@ public function getPeppolConfigRequest()
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -973,10 +973,10 @@ public function getPeppolPartiesRequest()
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1236,10 +1236,10 @@ public function getPeppolPartyConfigRequest($party_id)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1458,10 +1458,10 @@ public function removePeppolPartyConfigRequest($party_id)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1728,10 +1728,10 @@ public function requestPartyPrepareToMigrateRequest($party_id)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1983,10 +1983,10 @@ public function setPeppolConfigRequest($peppol_config = null)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -2261,10 +2261,10 @@ public function setPeppolPartyConfigRequest($party_id, $peppol_party_config = nu
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
diff --git a/lib/Api/PurchaseInvoiceApi.php b/lib/Api/PurchaseInvoiceApi.php
index ca4a43f..c2e3e3b 100644
--- a/lib/Api/PurchaseInvoiceApi.php
+++ b/lib/Api/PurchaseInvoiceApi.php
@@ -397,10 +397,10 @@ public function deletePurchaseInvoiceRequest($party_id, $document_id)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -709,10 +709,10 @@ public function downloadPurchaseInvoiceRequest($party_id, $document_id, $target_
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1002,10 +1002,10 @@ public function getPurchaseInvoiceStatusesRequest($party_id, $document_id)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1308,10 +1308,10 @@ public function queryRecipientPartyForInvoiceResponseRequest($party_id, $request
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1616,10 +1616,10 @@ public function recognizePurchaseInvoiceRequest($party_id, $file, $channel = nul
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1926,10 +1926,10 @@ public function sendInvoiceResponseRequest($party_id, $document_id, $invoice_res
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
diff --git a/lib/Api/PurchaseOrderApi.php b/lib/Api/PurchaseOrderApi.php
index 8a3a34f..f7bd68e 100644
--- a/lib/Api/PurchaseOrderApi.php
+++ b/lib/Api/PurchaseOrderApi.php
@@ -449,10 +449,10 @@ public function apiV1PartyIdPurchaseOrderDocumentIdStatusGetRequest($party_id, $
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -770,10 +770,10 @@ public function apiV1PartyIdPurchaseOrderQueryRecipientPartyPostRequest($party_i
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1080,10 +1080,10 @@ public function sendOrderCancellationRequest($party_id, $document_id, $order_can
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1407,10 +1407,10 @@ public function sendPurchaseOrderRequest($party_id, $file, $receiver_id = null,
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
diff --git a/lib/Api/SalesInvoiceApi.php b/lib/Api/SalesInvoiceApi.php
index 1f2bcb8..17a9667 100644
--- a/lib/Api/SalesInvoiceApi.php
+++ b/lib/Api/SalesInvoiceApi.php
@@ -449,10 +449,10 @@ public function getSalesInvoiceStatusesRequest($party_id, $document_id)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -755,10 +755,10 @@ public function queryRecipientPartyForSalesInvoiceRequest($party_id, $request_bo
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1063,10 +1063,10 @@ public function recognizeSalesInvoiceRequest($party_id, $file, $channel = null)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1390,10 +1390,10 @@ public function sendSalesInvoiceRequest($party_id, $file, $receiver_id = null, $
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+		$defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
diff --git a/lib/Api/SalesOrderApi.php b/lib/Api/SalesOrderApi.php
index 3c50290..1200422 100644
--- a/lib/Api/SalesOrderApi.php
+++ b/lib/Api/SalesOrderApi.php
@@ -397,10 +397,10 @@ public function deleteSalesOrderRequest($party_id, $document_id)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+		$defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -709,10 +709,10 @@ public function downloadSalesOrderRequest($party_id, $document_id, $target_forma
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1002,10 +1002,10 @@ public function getSalesOrderStatusesRequest($party_id, $document_id)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1308,10 +1308,10 @@ public function queryRecipientPartyForOrderResponseRequest($party_id, $request_b
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1618,10 +1618,10 @@ public function sendOrderResponseRequest($party_id, $document_id, $order_respons
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
diff --git a/lib/Api/UserApi.php b/lib/Api/UserApi.php
index bc2df39..720ae8d 100644
--- a/lib/Api/UserApi.php
+++ b/lib/Api/UserApi.php
@@ -415,10 +415,10 @@ public function addOrUpdateUserRequest($user = null)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+		$defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -698,10 +698,10 @@ public function addOrUpdateUserPartyRequest($name, $user_party)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -912,10 +912,10 @@ public function deleteUserRequest($name)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1145,10 +1145,10 @@ public function deleteUserPartyRequest($name, $party_id)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1411,10 +1411,10 @@ public function getUserPartiesRequest($name)
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
@@ -1658,10 +1658,10 @@ public function getUsersRequest()
             $headers['Authorization'] = 'Bearer ' . $this->config->getAccessToken();
         }
 
-        $defaultHeaders = [];
-        if ($this->config->getUserAgent()) {
-            $defaultHeaders['User-Agent'] = $this->config->getUserAgent();
-        }
+        $defaultHeaders = $this->config->getDefaultHeaders();
+		if ($this->config->getUserAgent()) {
+			$defaultHeaders['User-Agent'] = $this->config->getUserAgent();
+		}
 
         $headers = array_merge(
             $defaultHeaders,
diff --git a/lib/Configuration.php b/lib/Configuration.php
index 471d4da..0a1247e 100644
--- a/lib/Configuration.php
+++ b/lib/Configuration.php
@@ -103,6 +103,13 @@ class Configuration
      * @var string
      */
     protected $userAgent = 'OpenAPI-Generator/1.0.0/PHP';
+	
+	/**
+	 * Default headers (custom headers) to apply to all requests.
+	 *
+	 * @var array<string,string>
+	 */
+	protected $defaultHeaders = [];
 
     /**
      * Debug switch (default set to false)
@@ -329,6 +336,41 @@ public function getUserAgent()
         return $this->userAgent;
     }
 
+	/**
+	 * Gets default headers.
+	 * 
+	 * @return array<string,string>
+	 */
+	public function getDefaultHeaders(): array
+	{
+		return $this->defaultHeaders;
+	}
+
+	/**
+	 * Sets default headers.
+	 * 
+	 * @param array<string,string> $headers
+	 * @return $this
+	 */
+	public function setDefaultHeaders(array $headers)
+	{
+		$this->defaultHeaders = $headers;
+		return $this;
+	}
+
+	/**
+	 * Adds a default header.
+	 * 
+	 * @param string $name
+	 * @param string $value
+	 * @return $this
+	 */
+	public function addDefaultHeader(string $name, string $value)
+	{
+		$this->defaultHeaders[$name] = $value;
+		return $this;
+	}
+
     /**
      * Sets debug flag
      *