diff --git a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/ApiClient.mustache b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/ApiClient.mustache
index db61206af3f..072a496232d 100644
--- a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/ApiClient.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/ApiClient.mustache
@@ -1524,9 +1524,11 @@ public class ApiClient {
                 File file = (File) param.getValue();
                 addPartToMultiPartBuilder(mpBuilder, param.getKey(), file);
             } else if (param.getValue() instanceof List) {
-                List<File> files = (List<File>) param.getValue();
-                for (File file : files) {
-                    addPartToMultiPartBuilder(mpBuilder, param.getKey(), file);
+                List list = (List) param.getValue();
+                for (Object item: list) {
+                    if (item instanceof File) {
+                        addPartToMultiPartBuilder(mpBuilder, param.getKey(), (File) item);
+                    }
                 }
             } else {
                 Headers partHeaders = Headers.of("Content-Disposition", "form-data; name=\"" + param.getKey() + "\"");
diff --git a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/build.gradle.mustache b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/build.gradle.mustache
index ecb504b6a43..5638aae2048 100644
--- a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/build.gradle.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/build.gradle.mustache
@@ -132,7 +132,7 @@ dependencies {
     implementation 'io.swagger.parser.v3:swagger-parser-v3:2.0.30'
     {{/dynamicOperations}}
     implementation "jakarta.annotation:jakarta.annotation-api:$jakarta_annotation_version"
-    testImplementation 'junit:junit:4.13.2'
+    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.8.2'
     testImplementation 'org.mockito:mockito-core:3.12.4'
 }
 
diff --git a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/build.sbt.mustache b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/build.sbt.mustache
index 762078b0a25..010ecb29a74 100644
--- a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/build.sbt.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/build.sbt.mustache
@@ -32,7 +32,7 @@ lazy val root = (project in file(".")).
       "jakarta.annotation" % "jakarta.annotation-api" % "1.3.5" % "compile",
       "com.google.code.findbugs" % "jsr305" % "3.0.2" % "compile",
       "jakarta.annotation" % "jakarta.annotation-api" % "1.3.5" % "compile",
-      "junit" % "junit" % "4.13.2" % "test",
+      "org.junit.jupiter" % "junit-jupiter-api" % "5.8.2" % "test",
       "com.novocode" % "junit-interface" % "0.10" % "test"
     )
   )
diff --git a/samples/client/others/java/okhttp-gson-streaming/build.gradle b/samples/client/others/java/okhttp-gson-streaming/build.gradle
index 651770024e0..85773c446ba 100644
--- a/samples/client/others/java/okhttp-gson-streaming/build.gradle
+++ b/samples/client/others/java/okhttp-gson-streaming/build.gradle
@@ -117,7 +117,7 @@ dependencies {
     implementation 'org.openapitools:jackson-databind-nullable:0.2.2'
     implementation group: 'org.apache.commons', name: 'commons-lang3', version: '3.12.0'
     implementation "jakarta.annotation:jakarta.annotation-api:$jakarta_annotation_version"
-    testImplementation 'junit:junit:4.13.2'
+    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.8.2'
     testImplementation 'org.mockito:mockito-core:3.12.4'
 }
 
diff --git a/samples/client/others/java/okhttp-gson-streaming/build.sbt b/samples/client/others/java/okhttp-gson-streaming/build.sbt
index 30d75ffead1..b4d6251b0de 100644
--- a/samples/client/others/java/okhttp-gson-streaming/build.sbt
+++ b/samples/client/others/java/okhttp-gson-streaming/build.sbt
@@ -21,7 +21,7 @@ lazy val root = (project in file(".")).
       "jakarta.annotation" % "jakarta.annotation-api" % "1.3.5" % "compile",
       "com.google.code.findbugs" % "jsr305" % "3.0.2" % "compile",
       "jakarta.annotation" % "jakarta.annotation-api" % "1.3.5" % "compile",
-      "junit" % "junit" % "4.13.2" % "test",
+      "org.junit.jupiter" % "junit-jupiter-api" % "5.8.2" % "test",
       "com.novocode" % "junit-interface" % "0.10" % "test"
     )
   )
diff --git a/samples/client/others/java/okhttp-gson-streaming/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/others/java/okhttp-gson-streaming/src/main/java/org/openapitools/client/ApiClient.java
index d2ad7c0d7b0..f607038fce9 100644
--- a/samples/client/others/java/okhttp-gson-streaming/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/others/java/okhttp-gson-streaming/src/main/java/org/openapitools/client/ApiClient.java
@@ -1319,9 +1319,11 @@ public class ApiClient {
                 File file = (File) param.getValue();
                 addPartToMultiPartBuilder(mpBuilder, param.getKey(), file);
             } else if (param.getValue() instanceof List) {
-                List<File> files = (List<File>) param.getValue();
-                for (File file : files) {
-                    addPartToMultiPartBuilder(mpBuilder, param.getKey(), file);
+                List list = (List) param.getValue();
+                for (Object item: list) {
+                    if (item instanceof File) {
+                        addPartToMultiPartBuilder(mpBuilder, param.getKey(), (File) item);
+                    }
                 }
             } else {
                 Headers partHeaders = Headers.of("Content-Disposition", "form-data; name=\"" + param.getKey() + "\"");
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/build.gradle b/samples/client/petstore/java/okhttp-gson-dynamicOperations/build.gradle
index 5dc5ebb696b..7d4c9665783 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/build.gradle
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/build.gradle
@@ -119,7 +119,7 @@ dependencies {
     implementation group: 'org.apache.commons', name: 'commons-lang3', version: '3.12.0'
     implementation 'io.swagger.parser.v3:swagger-parser-v3:2.0.30'
     implementation "jakarta.annotation:jakarta.annotation-api:$jakarta_annotation_version"
-    testImplementation 'junit:junit:4.13.2'
+    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.8.2'
     testImplementation 'org.mockito:mockito-core:3.12.4'
 }
 
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/build.sbt b/samples/client/petstore/java/okhttp-gson-dynamicOperations/build.sbt
index 92a66f0578f..6ed9d758834 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/build.sbt
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/build.sbt
@@ -23,7 +23,7 @@ lazy val root = (project in file(".")).
       "jakarta.annotation" % "jakarta.annotation-api" % "1.3.5" % "compile",
       "com.google.code.findbugs" % "jsr305" % "3.0.2" % "compile",
       "jakarta.annotation" % "jakarta.annotation-api" % "1.3.5" % "compile",
-      "junit" % "junit" % "4.13.2" % "test",
+      "org.junit.jupiter" % "junit-jupiter-api" % "5.8.2" % "test",
       "com.novocode" % "junit-interface" % "0.10" % "test"
     )
   )
diff --git a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/ApiClient.java
index 1a7343dc1cc..f5c30aa086b 100644
--- a/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/okhttp-gson-dynamicOperations/src/main/java/org/openapitools/client/ApiClient.java
@@ -1397,9 +1397,11 @@ public class ApiClient {
                 File file = (File) param.getValue();
                 addPartToMultiPartBuilder(mpBuilder, param.getKey(), file);
             } else if (param.getValue() instanceof List) {
-                List<File> files = (List<File>) param.getValue();
-                for (File file : files) {
-                    addPartToMultiPartBuilder(mpBuilder, param.getKey(), file);
+                List list = (List) param.getValue();
+                for (Object item: list) {
+                    if (item instanceof File) {
+                        addPartToMultiPartBuilder(mpBuilder, param.getKey(), (File) item);
+                    }
                 }
             } else {
                 Headers partHeaders = Headers.of("Content-Disposition", "form-data; name=\"" + param.getKey() + "\"");
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/build.gradle b/samples/client/petstore/java/okhttp-gson-parcelableModel/build.gradle
index 8947beb44f0..80cd5bef55e 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/build.gradle
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/build.gradle
@@ -118,7 +118,7 @@ dependencies {
     implementation group: 'org.apache.oltu.oauth2', name: 'org.apache.oltu.oauth2.client', version: '1.0.1'
     implementation group: 'org.apache.commons', name: 'commons-lang3', version: '3.12.0'
     implementation "jakarta.annotation:jakarta.annotation-api:$jakarta_annotation_version"
-    testImplementation 'junit:junit:4.13.2'
+    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.8.2'
     testImplementation 'org.mockito:mockito-core:3.12.4'
 }
 
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/build.sbt b/samples/client/petstore/java/okhttp-gson-parcelableModel/build.sbt
index f388de4d7c4..cacc65d7898 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/build.sbt
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/build.sbt
@@ -22,7 +22,7 @@ lazy val root = (project in file(".")).
       "jakarta.annotation" % "jakarta.annotation-api" % "1.3.5" % "compile",
       "com.google.code.findbugs" % "jsr305" % "3.0.2" % "compile",
       "jakarta.annotation" % "jakarta.annotation-api" % "1.3.5" % "compile",
-      "junit" % "junit" % "4.13.2" % "test",
+      "org.junit.jupiter" % "junit-jupiter-api" % "5.8.2" % "test",
       "com.novocode" % "junit-interface" % "0.10" % "test"
     )
   )
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/ApiClient.java
index 99943cfcaf8..8f45483a566 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/ApiClient.java
@@ -1398,9 +1398,11 @@ public class ApiClient {
                 File file = (File) param.getValue();
                 addPartToMultiPartBuilder(mpBuilder, param.getKey(), file);
             } else if (param.getValue() instanceof List) {
-                List<File> files = (List<File>) param.getValue();
-                for (File file : files) {
-                    addPartToMultiPartBuilder(mpBuilder, param.getKey(), file);
+                List list = (List) param.getValue();
+                for (Object item: list) {
+                    if (item instanceof File) {
+                        addPartToMultiPartBuilder(mpBuilder, param.getKey(), (File) item);
+                    }
                 }
             } else {
                 Headers partHeaders = Headers.of("Content-Disposition", "form-data; name=\"" + param.getKey() + "\"");
diff --git a/samples/client/petstore/java/okhttp-gson/build.gradle b/samples/client/petstore/java/okhttp-gson/build.gradle
index aef2d813b88..670b7c8a0ba 100644
--- a/samples/client/petstore/java/okhttp-gson/build.gradle
+++ b/samples/client/petstore/java/okhttp-gson/build.gradle
@@ -118,7 +118,7 @@ dependencies {
     implementation group: 'org.apache.oltu.oauth2', name: 'org.apache.oltu.oauth2.client', version: '1.0.1'
     implementation group: 'org.apache.commons', name: 'commons-lang3', version: '3.12.0'
     implementation "jakarta.annotation:jakarta.annotation-api:$jakarta_annotation_version"
-    testImplementation 'junit:junit:4.13.2'
+    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.8.2'
     testImplementation 'org.mockito:mockito-core:3.12.4'
 }
 
diff --git a/samples/client/petstore/java/okhttp-gson/build.sbt b/samples/client/petstore/java/okhttp-gson/build.sbt
index fc2027ce75e..ca1c3c7e64d 100644
--- a/samples/client/petstore/java/okhttp-gson/build.sbt
+++ b/samples/client/petstore/java/okhttp-gson/build.sbt
@@ -22,7 +22,7 @@ lazy val root = (project in file(".")).
       "jakarta.annotation" % "jakarta.annotation-api" % "1.3.5" % "compile",
       "com.google.code.findbugs" % "jsr305" % "3.0.2" % "compile",
       "jakarta.annotation" % "jakarta.annotation-api" % "1.3.5" % "compile",
-      "junit" % "junit" % "4.13.2" % "test",
+      "org.junit.jupiter" % "junit-jupiter-api" % "5.8.2" % "test",
       "com.novocode" % "junit-interface" % "0.10" % "test"
     )
   )
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/ApiClient.java
index f813e6db9bb..e551cddfc65 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/ApiClient.java
@@ -1417,9 +1417,11 @@ public class ApiClient {
                 File file = (File) param.getValue();
                 addPartToMultiPartBuilder(mpBuilder, param.getKey(), file);
             } else if (param.getValue() instanceof List) {
-                List<File> files = (List<File>) param.getValue();
-                for (File file : files) {
-                    addPartToMultiPartBuilder(mpBuilder, param.getKey(), file);
+                List list = (List) param.getValue();
+                for (Object item: list) {
+                    if (item instanceof File) {
+                        addPartToMultiPartBuilder(mpBuilder, param.getKey(), (File) item);
+                    }
                 }
             } else {
                 Headers partHeaders = Headers.of("Content-Disposition", "form-data; name=\"" + param.getKey() + "\"");