diff --git a/samples/openapi3/client/petstore/java/jersey2-java8-special-characters/src/main/java/org/openapitools/client/JSON.java b/samples/openapi3/client/petstore/java/jersey2-java8-special-characters/src/main/java/org/openapitools/client/JSON.java
index 9d748f6e7c2..d29b48becb1 100644
--- a/samples/openapi3/client/petstore/java/jersey2-java8-special-characters/src/main/java/org/openapitools/client/JSON.java
+++ b/samples/openapi3/client/petstore/java/jersey2-java8-special-characters/src/main/java/org/openapitools/client/JSON.java
@@ -21,6 +21,7 @@ public class JSON implements ContextResolver<ObjectMapper> {
   public JSON() {
     mapper = new ObjectMapper();
     mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
+    mapper.configure(MapperFeature.ALLOW_COERCION_OF_SCALARS, false);
     mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, true);
     mapper.configure(DeserializationFeature.FAIL_ON_INVALID_SUBTYPE, true);
     mapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);