diff --git a/samples/client/petstore/java/okhttp-gson-nextgen/src/test/java/org/openapitools/client/JSONTest.java b/samples/client/petstore/java/okhttp-gson-nextgen/src/test/java/org/openapitools/client/JSONTest.java
index e7d783574f9..6b631a5a980 100644
--- a/samples/client/petstore/java/okhttp-gson-nextgen/src/test/java/org/openapitools/client/JSONTest.java
+++ b/samples/client/petstore/java/okhttp-gson-nextgen/src/test/java/org/openapitools/client/JSONTest.java
@@ -382,6 +382,8 @@ public class JSONTest {
             assertTrue(o.getActualInstance() instanceof BananaReq);
             BananaReq inst = (BananaReq) o.getActualInstance();
             assertEquals(inst.getLengthCm(), new java.math.BigDecimal(17));
+            assertEquals(json.getGson().toJson(o), "{\"lengthCm\":17}");
+            assertEquals(json.getGson().toJson(inst), "{\"lengthCm\":17}");
         }
         {
             // Try to deserialize empty object. This should fail 'oneOf' because none will match