diff --git a/modules/openapi-generator/src/main/resources/Java/libraries/jersey2/ApiClient.mustache b/modules/openapi-generator/src/main/resources/Java/libraries/jersey2/ApiClient.mustache
index 286838dcff..e9190a25cc 100644
--- a/modules/openapi-generator/src/main/resources/Java/libraries/jersey2/ApiClient.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/jersey2/ApiClient.mustache
@@ -1190,7 +1190,12 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
       }
     }
 
-    Invocation.Builder invocationBuilder = target.request().accept(accept);
+    Invocation.Builder invocationBuilder;
+    if (accept != null) {
+      invocationBuilder = target.request().accept(accept);
+    } else {
+      invocationBuilder = target.request();
+    }
 
     for (Entry<String, String> entry : cookieParams.entrySet()) {
       String value = entry.getValue();
diff --git a/samples/client/petstore/java/jersey2-java8-localdatetime/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/jersey2-java8-localdatetime/src/main/java/org/openapitools/client/ApiClient.java
index 5f4cb48efe..9ba931faa5 100644
--- a/samples/client/petstore/java/jersey2-java8-localdatetime/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/jersey2-java8-localdatetime/src/main/java/org/openapitools/client/ApiClient.java
@@ -1106,7 +1106,12 @@ public class ApiClient extends JavaTimeFormatter {
       }
     }
 
-    Invocation.Builder invocationBuilder = target.request().accept(accept);
+    Invocation.Builder invocationBuilder;
+    if (accept != null) {
+      invocationBuilder = target.request().accept(accept);
+    } else {
+      invocationBuilder = target.request();
+    }
 
     for (Entry<String, String> entry : cookieParams.entrySet()) {
       String value = entry.getValue();
diff --git a/samples/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java
index 5f4cb48efe..9ba931faa5 100644
--- a/samples/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java
@@ -1106,7 +1106,12 @@ public class ApiClient extends JavaTimeFormatter {
       }
     }
 
-    Invocation.Builder invocationBuilder = target.request().accept(accept);
+    Invocation.Builder invocationBuilder;
+    if (accept != null) {
+      invocationBuilder = target.request().accept(accept);
+    } else {
+      invocationBuilder = target.request();
+    }
 
     for (Entry<String, String> entry : cookieParams.entrySet()) {
       String value = entry.getValue();
diff --git a/samples/openapi3/client/extensions/x-auth-id-alias/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java b/samples/openapi3/client/extensions/x-auth-id-alias/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java
index 7f84407405..e6bb7d3fad 100644
--- a/samples/openapi3/client/extensions/x-auth-id-alias/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/openapi3/client/extensions/x-auth-id-alias/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java
@@ -1036,7 +1036,12 @@ public class ApiClient extends JavaTimeFormatter {
       }
     }
 
-    Invocation.Builder invocationBuilder = target.request().accept(accept);
+    Invocation.Builder invocationBuilder;
+    if (accept != null) {
+      invocationBuilder = target.request().accept(accept);
+    } else {
+      invocationBuilder = target.request();
+    }
 
     for (Entry<String, String> entry : cookieParams.entrySet()) {
       String value = entry.getValue();
diff --git a/samples/openapi3/client/petstore/java/jersey2-java8-special-characters/src/main/java/org/openapitools/client/ApiClient.java b/samples/openapi3/client/petstore/java/jersey2-java8-special-characters/src/main/java/org/openapitools/client/ApiClient.java
index 66eb9ca7f9..5fb5eda631 100644
--- a/samples/openapi3/client/petstore/java/jersey2-java8-special-characters/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/openapi3/client/petstore/java/jersey2-java8-special-characters/src/main/java/org/openapitools/client/ApiClient.java
@@ -981,7 +981,12 @@ public class ApiClient extends JavaTimeFormatter {
       }
     }
 
-    Invocation.Builder invocationBuilder = target.request().accept(accept);
+    Invocation.Builder invocationBuilder;
+    if (accept != null) {
+      invocationBuilder = target.request().accept(accept);
+    } else {
+      invocationBuilder = target.request();
+    }
 
     for (Entry<String, String> entry : cookieParams.entrySet()) {
       String value = entry.getValue();
diff --git a/samples/openapi3/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java b/samples/openapi3/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java
index 328fec6af9..5e115bca68 100644
--- a/samples/openapi3/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/openapi3/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/ApiClient.java
@@ -1190,7 +1190,12 @@ public class ApiClient extends JavaTimeFormatter {
       }
     }
 
-    Invocation.Builder invocationBuilder = target.request().accept(accept);
+    Invocation.Builder invocationBuilder;
+    if (accept != null) {
+      invocationBuilder = target.request().accept(accept);
+    } else {
+      invocationBuilder = target.request();
+    }
 
     for (Entry<String, String> entry : cookieParams.entrySet()) {
       String value = entry.getValue();