diff --git a/modules/openapi-generator/src/main/resources/Java/libraries/resttemplate/ApiClient.mustache b/modules/openapi-generator/src/main/resources/Java/libraries/resttemplate/ApiClient.mustache
index 5abf07fc02c..2a327daca24 100644
--- a/modules/openapi-generator/src/main/resources/Java/libraries/resttemplate/ApiClient.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/resttemplate/ApiClient.mustache
@@ -84,7 +84,7 @@ public class ApiClient {
             this.separator = separator;
         }
 
-        private String collectionToString(Collection<? extends CharSequence> collection) {
+        private String collectionToString(Collection<?> collection) {
             return StringUtils.collectionToDelimitedString(collection, separator);
         }
     }
@@ -407,7 +407,7 @@ public class ApiClient {
     * @param values The values of the parameter.
     * @return String representation of the parameter
     */
-    public String collectionPathParameterToString(CollectionFormat collectionFormat, Collection<? extends CharSequence> values) {
+    public String collectionPathParameterToString(CollectionFormat collectionFormat, Collection<?> values) {
         // create the value based on the collection format
         if (CollectionFormat.MULTI.equals(collectionFormat)) {
             // not valid for path params
diff --git a/modules/openapi-generator/src/main/resources/Java/libraries/webclient/ApiClient.mustache b/modules/openapi-generator/src/main/resources/Java/libraries/webclient/ApiClient.mustache
index fe6c6d14cb1..5437bb15b32 100644
--- a/modules/openapi-generator/src/main/resources/Java/libraries/webclient/ApiClient.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/webclient/ApiClient.mustache
@@ -76,7 +76,7 @@ public class ApiClient {
             this.separator = separator;
         }
 
-        private String collectionToString(Collection<? extends CharSequence> collection) {
+        private String collectionToString(Collection<?> collection) {
             return StringUtils.collectionToDelimitedString(collection, separator);
         }
     }
diff --git a/samples/client/petstore/java/resttemplate-withXml/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/resttemplate-withXml/src/main/java/org/openapitools/client/ApiClient.java
index 7c205678775..dbdccb6d1d8 100644
--- a/samples/client/petstore/java/resttemplate-withXml/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/resttemplate-withXml/src/main/java/org/openapitools/client/ApiClient.java
@@ -76,7 +76,7 @@ public class ApiClient {
             this.separator = separator;
         }
 
-        private String collectionToString(Collection<? extends CharSequence> collection) {
+        private String collectionToString(Collection<?> collection) {
             return StringUtils.collectionToDelimitedString(collection, separator);
         }
     }
@@ -395,7 +395,7 @@ public class ApiClient {
     * @param values The values of the parameter.
     * @return String representation of the parameter
     */
-    public String collectionPathParameterToString(CollectionFormat collectionFormat, Collection<? extends CharSequence> values) {
+    public String collectionPathParameterToString(CollectionFormat collectionFormat, Collection<?> values) {
         // create the value based on the collection format
         if (CollectionFormat.MULTI.equals(collectionFormat)) {
             // not valid for path params
diff --git a/samples/client/petstore/java/resttemplate/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/resttemplate/src/main/java/org/openapitools/client/ApiClient.java
index dd0f9ebd40d..7210077ec81 100644
--- a/samples/client/petstore/java/resttemplate/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/resttemplate/src/main/java/org/openapitools/client/ApiClient.java
@@ -71,7 +71,7 @@ public class ApiClient {
             this.separator = separator;
         }
 
-        private String collectionToString(Collection<? extends CharSequence> collection) {
+        private String collectionToString(Collection<?> collection) {
             return StringUtils.collectionToDelimitedString(collection, separator);
         }
     }
@@ -390,7 +390,7 @@ public class ApiClient {
     * @param values The values of the parameter.
     * @return String representation of the parameter
     */
-    public String collectionPathParameterToString(CollectionFormat collectionFormat, Collection<? extends CharSequence> values) {
+    public String collectionPathParameterToString(CollectionFormat collectionFormat, Collection<?> values) {
         // create the value based on the collection format
         if (CollectionFormat.MULTI.equals(collectionFormat)) {
             // not valid for path params
diff --git a/samples/client/petstore/java/webclient/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/webclient/src/main/java/org/openapitools/client/ApiClient.java
index efef2ba6047..779b6212b9f 100644
--- a/samples/client/petstore/java/webclient/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/webclient/src/main/java/org/openapitools/client/ApiClient.java
@@ -74,7 +74,7 @@ public class ApiClient {
             this.separator = separator;
         }
 
-        private String collectionToString(Collection<? extends CharSequence> collection) {
+        private String collectionToString(Collection<?> collection) {
             return StringUtils.collectionToDelimitedString(collection, separator);
         }
     }