diff --git a/src/main/java/io/falu/client/AbstractHttpApiClient.java b/src/main/java/io/falu/client/AbstractHttpApiClient.java
index 017af43..16cff30 100644
--- a/src/main/java/io/falu/client/AbstractHttpApiClient.java
+++ b/src/main/java/io/falu/client/AbstractHttpApiClient.java
@@ -76,16 +76,17 @@ protected <TResult> ResourceResponse<TResult> execute(Request.Builder builder, C
                     if (classOfTResult != null) {
                         result = objectMapper.readValue(body.charStream(), classOfTResult);
                     }
+                    break;
                 }
                 case 400: {
                     error = objectMapper.readValue(body.charStream(), HttpResponseProblem.class);
+                    break;
                 }
             }
-
-            // close the body stream
-            body.close();
         }
 
+        response.close();
+
         return (ResourceResponse<TResult>) ResourceResponse.builder()
             .statusCode(code)
             .headers(response.headers())
diff --git a/src/main/java/io/falu/networking/FaluApiClient.java b/src/main/java/io/falu/networking/FaluApiClient.java
index 1b49a87..d851610 100644
--- a/src/main/java/io/falu/networking/FaluApiClient.java
+++ b/src/main/java/io/falu/networking/FaluApiClient.java
@@ -59,6 +59,7 @@
 
 import java.io.IOException;
 import java.util.List;
+import java.util.UUID;
 
 public class FaluApiClient extends AbstractHttpApiClient {
     private static final String HOST = "api.falu.io";
@@ -75,20 +76,27 @@ public FaluApiClient(FaluClientOptions options, AppDetailsInterceptor intercepto
     }
 
     private static Request.Builder buildRequest(RequestOptions options) {
+        return buildRequest(options, null);
+    }
+
+    private static Request.Builder buildRequest(RequestOptions options, String method) {
         Request.Builder builder = new Request.Builder();
 
         if (options.workspace != null && !options.workspace.isEmpty()) {
             builder.header("X-Workspace-Id", options.workspace);
         }
 
+        // Check if idempotencyKey is not null and not empty
         if (options.idempotencyKey != null && !options.idempotencyKey.isEmpty()) {
             builder.header("X-Idempotency-Key", options.idempotencyKey);
+        } else if ("PATCH".equalsIgnoreCase(method) || "POST".equalsIgnoreCase(method)) {
+            // Generate a new UUID for idempotency key if method is PATCH or POST
+            builder.header("X-Idempotency-Key", UUID.randomUUID().toString());
         }
 
         boolean live = options.live != null && options.live;
         builder.header("X-Live-Mode", String.valueOf(live));
 
-
         return builder;
     }
 
@@ -145,7 +153,7 @@ public ResourceResponse<Payment> updatePayment(String paymentId, PaymentUpdateOp
     public ResourceResponse<Payment> createPayment(PaymentCreateOptions request, RequestOptions options) throws IOException {
         HttpUrl url = buildUrl("v1/payments/", null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(request), MEDIA_TYPE_JSON));
 
@@ -177,7 +185,7 @@ public ResourceResponse<PaymentAuthorization> updatePaymentAuthorization(String
 
         HttpUrl url = buildUrl("v1/payment_authorizations/" + authorizationId, null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "PATCH")
             .url(url)
             .patch(RequestBody.create(makeJson(updateOptions), MEDIA_TYPE_MERGE_PATCH_JSON));
 
@@ -187,7 +195,7 @@ public ResourceResponse<PaymentAuthorization> updatePaymentAuthorization(String
     public ResourceResponse<PaymentAuthorization> approvePaymentAuthorization(String authorizationId, RequestOptions options) throws IOException {
         HttpUrl url = buildUrl("v1/payment_authorizations/" + authorizationId + "/approve", null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(null), MEDIA_TYPE_JSON));
         return execute(builder, PaymentAuthorization.class);
@@ -196,7 +204,7 @@ public ResourceResponse<PaymentAuthorization> approvePaymentAuthorization(String
     public ResourceResponse<PaymentAuthorization> declinePaymentAuthorization(String authorizationId, RequestOptions options) throws IOException {
         HttpUrl url = buildUrl("v1/payment_authorizations/" + authorizationId + "/decline", null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(null), MEDIA_TYPE_JSON));
         return execute(builder, PaymentAuthorization.class);
@@ -215,7 +223,7 @@ public ResourceResponse<PaymentRefund[]> getPaymentRefunds(PaymentRefundsListOpt
     public ResourceResponse<PaymentRefund> createPaymentRefund(PaymentRefundCreateOptions request, RequestOptions options) throws IOException {
         HttpUrl url = buildUrl("v1/payment_refunds/", null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(request), MEDIA_TYPE_JSON));
 
@@ -238,7 +246,7 @@ public ResourceResponse<PaymentRefund> updatePaymentRefund(String refundId,
 
         HttpUrl url = buildUrl("v1/payment_refunds/" + refundId, null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "PATCH")
             .url(url)
             .patch(RequestBody.create(makeJson(updateOptions), MEDIA_TYPE_JSON));
 
@@ -259,7 +267,7 @@ public ResourceResponse<Message[]> getMessages(MessagesListOptions listOptions,
     public ResourceResponse<MessageResponse> createMessage(MessageCreateOptions request, RequestOptions options) throws IOException {
         HttpUrl url = buildUrl("v1/messages", null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(request), MEDIA_TYPE_JSON));
 
@@ -279,7 +287,7 @@ public ResourceResponse<Message> getMessage(String messageId, RequestOptions opt
     public ResourceResponse<Message> updateMessage(String messageId, MessageUpdateOptions updateOptions, RequestOptions options) throws IOException {
         HttpUrl url = buildUrl("v1/messages/" + messageId, null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "PATCH")
             .url(url)
             .patch(RequestBody.create(makeJson(updateOptions), MEDIA_TYPE_JSON));
 
@@ -289,7 +297,7 @@ public ResourceResponse<Message> updateMessage(String messageId, MessageUpdateOp
     public ResourceResponse<MessageResponse> sendBulkMessages(List<MessageCreateOptions> messages, RequestOptions options) throws IOException {
         HttpUrl url = buildUrl("v1/messages/batch", null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(messages), MEDIA_TYPE_JSON));
 
@@ -309,7 +317,7 @@ public ResourceResponse<MessageTemplate[]> getMessageTemplates(MessageTemplatesL
     public ResourceResponse<MessageTemplate> createMessageTemplate(MessageTemplateCreateOptions request, RequestOptions options) throws IOException {
         HttpUrl url = buildUrl("v1/message_templates", null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(request), MEDIA_TYPE_JSON));
 
@@ -329,7 +337,7 @@ public ResourceResponse<MessageTemplate> getMessageTemplate(String templateId, R
     public ResourceResponse<MessageTemplate> updateMessageTemplate(String templateId, MessageTemplateUpdateOptions patchModel, RequestOptions options) throws IOException {
         HttpUrl url = buildUrl("v1/message_templates/" + templateId, null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "PATCH")
             .url(url)
             .patch(RequestBody.create(makeJson(patchModel), MEDIA_TYPE_JSON));
 
@@ -349,7 +357,7 @@ public ResourceResponse<?> deleteMessageTemplate(String templateId, RequestOptio
     public ResourceResponse<MessageTemplateValidationResponse> validateMessageTemplate(MessageTemplateValidationRequest request, RequestOptions options) throws IOException {
         HttpUrl url = buildUrl("v1/message_templates/validate", null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(request), MEDIA_TYPE_JSON));
 
@@ -369,7 +377,7 @@ public ResourceResponse<MessageStream[]> getMessageStreams(MessageStreamsListOpt
     public ResourceResponse<MessageStream> createMessageStream(MessageStreamCreateOptions request, RequestOptions options) throws IOException {
         HttpUrl url = buildUrl("v1/message_streams", null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(request), MEDIA_TYPE_JSON));
 
@@ -389,7 +397,7 @@ public ResourceResponse<MessageStream> getMessageStream(String streamId, Request
     public ResourceResponse<MessageStream> updateMessageStream(String streamId, MessageStreamUpdateOptions updateOptions, RequestOptions options) throws IOException {
         HttpUrl url = buildUrl("v1/message_streams/" + streamId, null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "PATCH")
             .url(url)
             .patch(RequestBody.create(makeJson(updateOptions), MEDIA_TYPE_JSON));
 
@@ -410,7 +418,7 @@ public ResourceResponse<?> deleteMessageStream(String streamId, RequestOptions o
     public ResourceResponse<MessageStream> archiveMessageStream(String streamId, RequestOptions options) throws IOException {
         HttpUrl url = buildUrl("v1/message_streams/" + streamId + "/archive", null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(null), MEDIA_TYPE_JSON));
 
@@ -420,7 +428,7 @@ public ResourceResponse<MessageStream> archiveMessageStream(String streamId, Req
     public ResourceResponse<MessageStream> unarchiveMessageStream(String streamId, RequestOptions options) throws IOException {
         HttpUrl url = buildUrl("v1/message_streams/" + streamId + "/unarchive", null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(null), MEDIA_TYPE_JSON));
 
@@ -442,7 +450,7 @@ public ResourceResponse<MoneyBalance> getMoneyBalances(RequestOptions options) t
     public ResourceResponse<MoneyBalance> refreshMoneyBalances(RequestOptions options) throws IOException {
         HttpUrl url = buildUrl("v1/money_balances/refresh", null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(null), MEDIA_TYPE_JSON));
 
@@ -463,7 +471,7 @@ public ResourceResponse<Transfer[]> getTransfers(TransferListOptions listOptions
     public ResourceResponse<Transfer> createTransfer(TransferCreateOptions request, RequestOptions options) throws IOException {
         HttpUrl url = buildUrl("v1/transfers", null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(request), MEDIA_TYPE_JSON));
 
@@ -485,7 +493,7 @@ public ResourceResponse<Transfer> updateTransfer(String transferId, TransferUpda
 
         HttpUrl url = buildUrl("v1/transfers" + transferId, null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "PATCH")
             .url(url)
             .patch(RequestBody.create(makeJson(updateOptions), MEDIA_TYPE_JSON));
 
@@ -505,7 +513,7 @@ public ResourceResponse<TransferReversal[]> getTransferReversals(TransferReversa
     public ResourceResponse<TransferReversal> createTransferReversal(TransferReversalCreateOptions request, RequestOptions options) throws IOException {
         HttpUrl url = buildUrl("v1/transfer_reversals", null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(request), MEDIA_TYPE_JSON));
 
@@ -513,12 +521,11 @@ public ResourceResponse<TransferReversal> createTransferReversal(TransferReversa
     }
     //endregion
 
-    public ResourceResponse<TransferReversal> updateTransferReversal(String transferId,
-                                                                     TransferReversalUpdateOptions updateOptions, RequestOptions options) throws IOException {
+    public ResourceResponse<TransferReversal> updateTransferReversal(String transferId, TransferReversalUpdateOptions updateOptions, RequestOptions options) throws IOException {
 
         HttpUrl url = buildUrl("v1/transfer_reversals/" + transferId, null);
 
-        Request.Builder builder = buildRequest(options)
+        Request.Builder builder = buildRequest(options, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(updateOptions), MEDIA_TYPE_JSON));
 
@@ -572,7 +579,7 @@ public ResourceResponse<File> uploadFile(FileCreateOptions request, RequestOptio
 
         RequestBody requestBody = bodyBuilder.build();
 
-        Request.Builder builder = buildRequest(requestOptions)
+        Request.Builder builder = buildRequest(requestOptions, "POST")
             .url(url)
             .post(requestBody);
 
@@ -592,7 +599,7 @@ public ResourceResponse<FileLink[]> getFileLinks(FileLinksListOptions listOption
     public ResourceResponse<FileLink> createFileLink(FileLinkCreateOptions request, RequestOptions requestOptions) throws IOException {
         HttpUrl url = buildUrl("v1/file_links", null);
 
-        Request.Builder builder = buildRequest(requestOptions)
+        Request.Builder builder = buildRequest(requestOptions, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(request), MEDIA_TYPE_JSON));
 
@@ -612,7 +619,7 @@ public ResourceResponse<FileLink> getFileLink(String linkId, RequestOptions requ
     public ResourceResponse<FileLink> updateFileLink(String linkId, FileLinkUpdateOptions updateOptions, RequestOptions requestOptions) throws IOException {
         HttpUrl url = buildUrl("v1/file_links/" + linkId, null);
 
-        Request.Builder builder = buildRequest(requestOptions)
+        Request.Builder builder = buildRequest(requestOptions, "PATCH")
             .url(url)
             .patch(RequestBody.create(makeJson(updateOptions), MEDIA_TYPE_MERGE_PATCH_JSON));
 
@@ -632,7 +639,7 @@ public ResourceResponse<WebhookEndpoint[]> getWebhookEndpoints(WebhookEndpointLi
 
     public ResourceResponse<WebhookEndpoint> createWebhookEndpoint(WebhookEndpointCreateRequest request, RequestOptions requestOptions) throws IOException {
         HttpUrl url = buildUrl("v1/webhooks/endpoints", null);
-        Request.Builder builder = buildRequest(requestOptions)
+        Request.Builder builder = buildRequest(requestOptions, "PATCH")
             .url(url)
             .post(RequestBody.create(makeJson(request), MEDIA_TYPE_JSON));
 
@@ -654,7 +661,7 @@ public ResourceResponse<WebhookEndpoint> updateWebhookEndpoint(String endpointId
 
         HttpUrl url = buildUrl("v1/webhooks/endpoints/" + endpointId, null);
 
-        Request.Builder builder = buildRequest(requestOptions)
+        Request.Builder builder = buildRequest(requestOptions, "PATCH")
             .url(url)
             .patch(RequestBody.create(makeJson(updateOptions), MEDIA_TYPE_JSON));
         return execute(builder, WebhookEndpoint.class);
@@ -705,7 +712,7 @@ public ResourceResponse<IdentityVerification[]> getIdentityVerifications(Identit
     public ResourceResponse<IdentityVerification> createIdentityVerification(IdentityVerificationCreateOptions request, RequestOptions requestOptions) throws IOException {
         HttpUrl url = buildUrl("v1/identity/verifications", null);
 
-        Request.Builder builder = buildRequest(requestOptions)
+        Request.Builder builder = buildRequest(requestOptions, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(request), MEDIA_TYPE_JSON));
 
@@ -726,7 +733,7 @@ public ResourceResponse<IdentityVerification> updateIdentityVerification(String
                                                                              IdentityVerificationUpdateOptions updateOptions, RequestOptions requestOptions) throws IOException {
         HttpUrl url = buildUrl("v1/identity/verifications/" + id, null);
 
-        Request.Builder builder = buildRequest(requestOptions)
+        Request.Builder builder = buildRequest(requestOptions, "PATCH")
             .url(url)
             .patch(RequestBody.create(makeJson(updateOptions), MEDIA_TYPE_JSON));
 
@@ -747,7 +754,7 @@ public ResourceResponse<IdentityVerification> cancelIdentityVerification(String
     public ResourceResponse<IdentityVerification> redactIdentityVerification(String id, RequestOptions requestOptions) throws IOException {
         HttpUrl url = buildUrl("v1/identity/verifications/" + id + "/redact", null);
 
-        Request.Builder builder = buildRequest(requestOptions)
+        Request.Builder builder = buildRequest(requestOptions, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(null), MEDIA_TYPE_JSON));
 
@@ -781,7 +788,7 @@ public ResourceResponse<IdentityVerificationReport> getIdentityVerificationRepor
     public ResourceResponse<TemporaryKey> createTemporaryKey(TemporaryKeyCreateOptions request, RequestOptions requestOptions) throws IOException {
         HttpUrl url = buildUrl("v1/temporary_keys", null);
 
-        Request.Builder builder = buildRequest(requestOptions)
+        Request.Builder builder = buildRequest(requestOptions, "POST")
             .url(url)
             .post(RequestBody.create(makeJson(request), MEDIA_TYPE_JSON));
         return execute(builder, TemporaryKey.class);