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 c222c57c6ba..218f5452ce2 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
@@ -988,8 +988,8 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
     if (contentType.startsWith("multipart/form-data")) {
       MultiPart multiPart = new MultiPart();
       for (Entry<String, Object> param: formParams.entrySet()) {
-        if (param.getValue() instanceof Iterable) {
-          ((Iterable)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
+        if (param.getValue() instanceof Iterable<?>) {
+          ((Iterable<?>)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
         } else {
           addParamToMultipart(param.getValue(), param.getKey(), multiPart);
         }
diff --git a/modules/openapi-generator/src/main/resources/Java/libraries/jersey3/ApiClient.mustache b/modules/openapi-generator/src/main/resources/Java/libraries/jersey3/ApiClient.mustache
index f83bccd7704..046a9f9bc8f 100644
--- a/modules/openapi-generator/src/main/resources/Java/libraries/jersey3/ApiClient.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/jersey3/ApiClient.mustache
@@ -988,8 +988,8 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
     if (contentType.startsWith("multipart/form-data")) {
       MultiPart multiPart = new MultiPart();
       for (Entry<String, Object> param: formParams.entrySet()) {
-        if (param.getValue() instanceof Iterable) {
-          ((Iterable)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
+        if (param.getValue() instanceof Iterable<?>) {
+          ((Iterable<?>)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
         } else {
           addParamToMultipart(param.getValue(), param.getKey(), multiPart);
         }
diff --git a/samples/client/others/java/jersey2-oneOf-Mixed/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/others/java/jersey2-oneOf-Mixed/src/main/java/org/openapitools/client/ApiClient.java
index 747fa1e3ee1..f6bc323519a 100644
--- a/samples/client/others/java/jersey2-oneOf-Mixed/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/others/java/jersey2-oneOf-Mixed/src/main/java/org/openapitools/client/ApiClient.java
@@ -767,8 +767,8 @@ public class ApiClient extends JavaTimeFormatter {
     if (contentType.startsWith("multipart/form-data")) {
       MultiPart multiPart = new MultiPart();
       for (Entry<String, Object> param: formParams.entrySet()) {
-        if (param.getValue() instanceof Iterable) {
-          ((Iterable)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
+        if (param.getValue() instanceof Iterable<?>) {
+          ((Iterable<?>)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
         } else {
           addParamToMultipart(param.getValue(), param.getKey(), multiPart);
         }
diff --git a/samples/client/others/java/jersey2-oneOf-duplicates/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/others/java/jersey2-oneOf-duplicates/src/main/java/org/openapitools/client/ApiClient.java
index 747fa1e3ee1..f6bc323519a 100644
--- a/samples/client/others/java/jersey2-oneOf-duplicates/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/others/java/jersey2-oneOf-duplicates/src/main/java/org/openapitools/client/ApiClient.java
@@ -767,8 +767,8 @@ public class ApiClient extends JavaTimeFormatter {
     if (contentType.startsWith("multipart/form-data")) {
       MultiPart multiPart = new MultiPart();
       for (Entry<String, Object> param: formParams.entrySet()) {
-        if (param.getValue() instanceof Iterable) {
-          ((Iterable)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
+        if (param.getValue() instanceof Iterable<?>) {
+          ((Iterable<?>)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
         } else {
           addParamToMultipart(param.getValue(), param.getKey(), multiPart);
         }
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 176ad35d9f8..74e7c4e95af 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
@@ -908,8 +908,8 @@ public class ApiClient extends JavaTimeFormatter {
     if (contentType.startsWith("multipart/form-data")) {
       MultiPart multiPart = new MultiPart();
       for (Entry<String, Object> param: formParams.entrySet()) {
-        if (param.getValue() instanceof Iterable) {
-          ((Iterable)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
+        if (param.getValue() instanceof Iterable<?>) {
+          ((Iterable<?>)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
         } else {
           addParamToMultipart(param.getValue(), param.getKey(), multiPart);
         }
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 176ad35d9f8..74e7c4e95af 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
@@ -908,8 +908,8 @@ public class ApiClient extends JavaTimeFormatter {
     if (contentType.startsWith("multipart/form-data")) {
       MultiPart multiPart = new MultiPart();
       for (Entry<String, Object> param: formParams.entrySet()) {
-        if (param.getValue() instanceof Iterable) {
-          ((Iterable)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
+        if (param.getValue() instanceof Iterable<?>) {
+          ((Iterable<?>)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
         } else {
           addParamToMultipart(param.getValue(), param.getKey(), multiPart);
         }
diff --git a/samples/client/petstore/java/jersey3-oneOf/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/jersey3-oneOf/src/main/java/org/openapitools/client/ApiClient.java
index eac50c8ba37..c1a0d1d3514 100644
--- a/samples/client/petstore/java/jersey3-oneOf/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/jersey3-oneOf/src/main/java/org/openapitools/client/ApiClient.java
@@ -767,8 +767,8 @@ public class ApiClient extends JavaTimeFormatter {
     if (contentType.startsWith("multipart/form-data")) {
       MultiPart multiPart = new MultiPart();
       for (Entry<String, Object> param: formParams.entrySet()) {
-        if (param.getValue() instanceof Iterable) {
-          ((Iterable)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
+        if (param.getValue() instanceof Iterable<?>) {
+          ((Iterable<?>)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
         } else {
           addParamToMultipart(param.getValue(), param.getKey(), multiPart);
         }
diff --git a/samples/client/petstore/java/jersey3/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/jersey3/src/main/java/org/openapitools/client/ApiClient.java
index 1c7368d6eb1..ced1070adf2 100644
--- a/samples/client/petstore/java/jersey3/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/jersey3/src/main/java/org/openapitools/client/ApiClient.java
@@ -990,8 +990,8 @@ public class ApiClient extends JavaTimeFormatter {
     if (contentType.startsWith("multipart/form-data")) {
       MultiPart multiPart = new MultiPart();
       for (Entry<String, Object> param: formParams.entrySet()) {
-        if (param.getValue() instanceof Iterable) {
-          ((Iterable)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
+        if (param.getValue() instanceof Iterable<?>) {
+          ((Iterable<?>)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
         } else {
           addParamToMultipart(param.getValue(), param.getKey(), multiPart);
         }
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 98f1e7029dd..42014df09e5 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
@@ -816,8 +816,8 @@ public class ApiClient extends JavaTimeFormatter {
     if (contentType.startsWith("multipart/form-data")) {
       MultiPart multiPart = new MultiPart();
       for (Entry<String, Object> param: formParams.entrySet()) {
-        if (param.getValue() instanceof Iterable) {
-          ((Iterable)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
+        if (param.getValue() instanceof Iterable<?>) {
+          ((Iterable<?>)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
         } else {
           addParamToMultipart(param.getValue(), param.getKey(), multiPart);
         }
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 51250558848..b130658a0c7 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
@@ -767,8 +767,8 @@ public class ApiClient extends JavaTimeFormatter {
     if (contentType.startsWith("multipart/form-data")) {
       MultiPart multiPart = new MultiPart();
       for (Entry<String, Object> param: formParams.entrySet()) {
-        if (param.getValue() instanceof Iterable) {
-          ((Iterable)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
+        if (param.getValue() instanceof Iterable<?>) {
+          ((Iterable<?>)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
         } else {
           addParamToMultipart(param.getValue(), param.getKey(), multiPart);
         }
diff --git a/samples/openapi3/client/petstore/java/jersey2-java8-swagger1/src/main/java/org/openapitools/client/ApiClient.java b/samples/openapi3/client/petstore/java/jersey2-java8-swagger1/src/main/java/org/openapitools/client/ApiClient.java
index bc824775c3b..2c7b46e9d24 100644
--- a/samples/openapi3/client/petstore/java/jersey2-java8-swagger1/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/openapi3/client/petstore/java/jersey2-java8-swagger1/src/main/java/org/openapitools/client/ApiClient.java
@@ -892,8 +892,8 @@ public class ApiClient extends JavaTimeFormatter {
     if (contentType.startsWith("multipart/form-data")) {
       MultiPart multiPart = new MultiPart();
       for (Entry<String, Object> param: formParams.entrySet()) {
-        if (param.getValue() instanceof Iterable) {
-          ((Iterable)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
+        if (param.getValue() instanceof Iterable<?>) {
+          ((Iterable<?>)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
         } else {
           addParamToMultipart(param.getValue(), param.getKey(), multiPart);
         }
diff --git a/samples/openapi3/client/petstore/java/jersey2-java8-swagger2/src/main/java/org/openapitools/client/ApiClient.java b/samples/openapi3/client/petstore/java/jersey2-java8-swagger2/src/main/java/org/openapitools/client/ApiClient.java
index bc824775c3b..2c7b46e9d24 100644
--- a/samples/openapi3/client/petstore/java/jersey2-java8-swagger2/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/openapi3/client/petstore/java/jersey2-java8-swagger2/src/main/java/org/openapitools/client/ApiClient.java
@@ -892,8 +892,8 @@ public class ApiClient extends JavaTimeFormatter {
     if (contentType.startsWith("multipart/form-data")) {
       MultiPart multiPart = new MultiPart();
       for (Entry<String, Object> param: formParams.entrySet()) {
-        if (param.getValue() instanceof Iterable) {
-          ((Iterable)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
+        if (param.getValue() instanceof Iterable<?>) {
+          ((Iterable<?>)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
         } else {
           addParamToMultipart(param.getValue(), param.getKey(), multiPart);
         }
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 6b33ddde349..9ff1ff30c0b 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
@@ -990,8 +990,8 @@ public class ApiClient extends JavaTimeFormatter {
     if (contentType.startsWith("multipart/form-data")) {
       MultiPart multiPart = new MultiPart();
       for (Entry<String, Object> param: formParams.entrySet()) {
-        if (param.getValue() instanceof Iterable) {
-          ((Iterable)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
+        if (param.getValue() instanceof Iterable<?>) {
+          ((Iterable<?>)param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
         } else {
           addParamToMultipart(param.getValue(), param.getKey(), multiPart);
         }