diff --git a/bin/configs/java-jersey2-8.yaml b/bin/configs/java-jersey2-8.yaml
index ca0452d33e3eb..e4407a08260b2 100644
--- a/bin/configs/java-jersey2-8.yaml
+++ b/bin/configs/java-jersey2-8.yaml
@@ -11,3 +11,4 @@ additionalProperties:
   useOneOfDiscriminatorLookup: true
   disallowAdditionalPropertiesIfNotPresent: false
   gradleProperties: "\n# JVM arguments\norg.gradle.jvmargs=-Xmx2024m -XX:MaxPermSize=512m\n# set timeout\norg.gradle.daemon.idletimeout=3600000\n# show all warnings\norg.gradle.warning.mode=all"
+  failOnUnknownProperties: true
\ No newline at end of file
diff --git a/samples/openapi3/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/JSON.java b/samples/openapi3/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/JSON.java
index 543741c20100b..a17316c3de29a 100644
--- a/samples/openapi3/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/JSON.java
+++ b/samples/openapi3/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/JSON.java
@@ -23,7 +23,7 @@ public JSON() {
     mapper = JsonMapper.builder()
             .serializationInclusion(JsonInclude.Include.NON_NULL)
             .configure(MapperFeature.ALLOW_COERCION_OF_SCALARS, false)
-            .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
+            .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, true)
             .configure(DeserializationFeature.FAIL_ON_INVALID_SUBTYPE, true)
             .disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
             .enable(SerializationFeature.WRITE_ENUMS_USING_TO_STRING)