Update EnumTest.java

Author: eric-rolli

samples/server/petstore/jaxrs/jersey2-useTags/src/gen/java/org/openapitools/model/EnumTest.java

@@ -139,7 +139,7 @@ public Integer getValue() {
     }
 
     @Override
-    public Integer toString() {
+    public String toString() {
       return String.valueOf(value);
     }